New to home repairs

[DumbPCuser]

As title suggests im new at this, so plese go eesy on me.
I have a laptop i am trying to replace the screen on: Compaq Presario C700 (fixing old laptops as a learning/exp tool)
I ordered a ‘new’ used screen which i replaced the old one with, this is where the problem begins.
I put on the new screen, and the computer wouldnt even turn on. power light would activate for, like, half a second then nothing. So i put the old screen back on which at that stage the computer itself worked (turned on-but screen horribly damaged).
So i presumed the ‘new’ screen was defective, and decided to try and get the new screen active by using the old screens parts: ?alternator/adaptor bar? for the LED backlight (my terminology may be incorrect here), and the 30?/40? pin cable that connects to the back of the LCD screen.
Bad move.
Now the old cracked screen that at least the computer powered on with, no longer powers on.
So, a few questions for those that are far more adept at PC repair than some dumb noob.

Can what i have done by switching out components cause more damage to the other once working components, if those components were shorted and respectively cause further shorting? (i dont even know if that makes sense or is a thing, forgive me)

What would cause a screen to prevent the laptop from powering on?

Can anyone provide some recommendations/information to help locate with precision the fault?

Is there any other questions i should be asking that im not?

I have switched out the screens about 3 times each now, with 2 of those times being carefully inspecting the cables are mounted correctly (to which, there may be something simple a noob is missing)
I wish to avoid paying for someone to rectify this for me, as I wish to rectify it myself and learn valuable in the process.
I would greatly appreciate any input from more experienced users, but go easy on the jargon, im new at this.

[veeg]

Hello

See if this helps..

[MEDIA=youtube]FlzS80dVOUs[/MEDIA]

[DumbPCuser]

Thankyou veeg for your response, it was in fact videos like the one you posted that inspired me to try a screen replacement. I must have viewed at least 8 different ones like it. Alas, it does not really help that much at all. Actually replacing the screen is not the issue, i have done that upwards of six times now, my issues are getting the screen working. I have detailed the issues to the best of my ability in OP.
Thankyou again for your input.

[PeterOz]

I ordered a ‘new’ used screen which i replaced the old one with

Were they the exact same screen.
A lot of laptops have same model numbers but different screens - not swap-able
They must be like for like.

[Bruce]

While I have to take my hat off to you for even attempting this task, I have to also say, you need to know when you are out of your league.
Yes, it’s the best way to learn, to dive in and get your hands dirty, but having pulled many laptops apart, I know all too well how simply they can break.
From the flimsy plastic molding to those damn ribbon strips and their little docking clips.

My first guess is the ‘new’ screen was either also damaged, or not compatible.

[DumbPCuser]

Were they the exact same screen.
A lot of laptops have same model numbers but different screens - not swap-able
They must be like for like.

This is a great question, to which i cannot answer in great detail. The screen i bought sported the same model numbers on the top right corner of the plastic casing: C700. It in fact looked identical, Is it possible they were not?
Thankyou very much for you response/question in helping me locate the issue.

[DumbPCuser]

While I have to take my hat off to you for even attempting this task, I have to also say, you need to know when you are out of your league.
Yes, it’s the best way to learn, to dive in and get your hands dirty, but having pulled many laptops apart, I know all too well how simply they can break.
From the flimsy plastic molding to those **** ribbon strips and their little docking clips.

My first guess is the ‘new’ screen was either also damaged, or not compatible.

Hi Bruce, thanks for the response.
Your assertion may be correct, and the task may have been beyond me. But I would also contend that doesnt explain how I could put the old screen back on at least twice before it all went pear shaped. The best form of learning is having a go, right?
To the best of my knowledge no ribbons or docking clips are/were broken (from a visually observable perspective, anyway).

Can these ribbons and docking clips break without being visually observable, and how fragile are these things?

Is it possible that a screen off the exact same model Presario C700 assembly was not compatible?

The ‘new’ screen may also have been damaged as you postulated, could utilising damaged parts from that screen on the old cracked screen have caused further issues with the pre-working (albeit damaged/cracked) screen, further causing it to not work after a third switch around?
Answers to these questions would be very much appreciated.

[DumbPCuser]

Were they the exact same screen.
A lot of laptops have same model numbers but different screens - not swap-able
They must be like for like.

Are there any numbers/identifying indicators on the back of the screen you can recommend checking, and i may be able to give you (and myself) a proper answer to this line of questioning?

[PeterOz]

Are there any numbers/identifying indicators on the back of the screen you can recommend checking,

It all depends on

1. Is the supplier reputable and puts that info on.
2. Is the screen brand new (yours is not) or has the sticker fallen off as the glue is weakened by the heat.
3. Is the new screen any good - even a brand new screen can be DOA

by using the old screens parts:

Even if the parts look the same it does not mean the same.
Something as simple as a cable can look the same but unless you know the part number is exactly the same.
No revision numbers then the cable can be terminated differently, you then have to bell out the connectors.

Many Many parts look the same it is only when you start to read the id names/numbers that you can be sure they are the same.

Can what i have done by switching out components cause more damage to the other once working components

Yes

Can anyone provide some recommendations/information to help locate with precision the fault?

You either need experience - not you (Please do not take this comment the wrong way we all had to learn)
OR
a service manual to show what outputs you should be getting from each component.

[Bruce]

When you say you got a ‘new’ screen, do you mean the LCD panel that goes into the hinged screen top of a laptop, or the whole hinged part itself - complete with all the LCD stuff inside the outer casing?

But to answer your questions…
a) 100% it’s a great way to learn, only surpassed by someone teaching you first
b) if you are replacing the LCD panel and backlight components that then go into the outer shell casing then yes, many things can go pear shaped
c) laptop manufactures change their models very regularly, so while getting the same screen for your model should be a good indicator, it is no guarantee. For example, were they the same motherboards?
d) as to utilising bad parts, it all depends on what the damage was. If there was a shorted circuit, or a faulty power flow issue, then that would have effected the target component as well

[PeterOz]

re there any numbers/identifying indicators

[ATTACH type=“full”]13549[/ATTACH]

[DumbPCuser]

Thankyou all so much for your answers @Bruce and @PeterOz. Very informative both of you.
I will look into what both of you have said further and respond. From memory, some numbers may have been different by one value.
These answers are incredibly informative, and give me plenty to think about and inspect. I will definitely keep you both posted as you have been more than accommodating of my requests, I will probably ask for some advice on purchasing YET ANOTHER screen and maybe some ribbons and such.

The purchase was not from a ‘reputable’ dealer per se, it was from an ebay seller, and the screen i purchased was the whole screen assembly including the front and back case and brackets, ribbons, cables, adapter bar: sold as the ‘screen assembly’.

I am going to sleep. I will get started on answering your questions in more detail in the next few hours/tomorrow (depending on your time zone).
Again, thankyou both very much for the intuitive and timely responses. I believe they may serve as very good guides to get me going in the right direction.
I think (if i knew about) ‘Rule 2)’ would have been very beneficial in my circumstances, it is a shame i wasnt aware of/practiced it. I was in doubt and did just about everything and anything.

I look forward to responding to you both in detail in the very near future.
Thankyou both so much.

[DumbPCuser]

I am one of those fools that learns from mistakes.

[PeterOz]

I am one of those fools that learns from mistakes

If you learn then it is a good mistake.

[Bruce]

And it’ll be remembered longer - well, hopefully.
Happy Shopping!