How to backup SSD if MacBook doesn't turn on? I have a MacBook Pro 15" Mid 2015 and after 3 years of using it, I think it is broken since it won't power on. I already tried resetting SMC and NVRAM but it's still not working. I don't hear any chimes or any fan noises and my charger is still working properly. I tried charging it for more than 3 hours but the light is always orange/amber. I guess this is a logic board issue.

I went to an Apple Center to get it fixed but they advised me to backup my SSD first because they don't do this service and they will wipe all of my files so they can diagnose it properly.

So my question is:

How do I backup my SSD when my MacBook doesn't even turn on? I'm guessing I need to remove the SSD but I don't know what to do after remove it.
How do I backup my SSD when my MacBook doesn't even turn on? I'm
guessing I need to remove the SSD but I don't know what to do after
remove it.

You are correct; you just need to remove it.
What you do afterwards is put it in a safe place (like a desk drawer).
Why?
There's no need to erase, much less even have, an internal SSD to diagnose and repair a power issue.
If the &quot;Apple Center&quot; (you didn't say if they were an actual Apple Store or an authorized 3rd party repair facility) said that &quot;wiping&quot; the drive was necessary, I would look for another facility.
You can boot a MacBook from USB, another SSD, or from another MacBook (via Target Disk Mode) so there's no reason that they should get yours (as a side note, they should have spare ones with clean OSes for diagnostics). An internal drive is absolutely not necessary for diagnosis/repairs (unless of course the issue is the SSD itself). As it's a power issue, the SSD is irrelevant and shouldn't even be touched.
The fix...
The problem that you are experiencing is related to the DC-in board (aka the MagSafe board).

Besides being the interface for your charger to your MacBook, it acts as a safeguard to ensure that you're not dumping 18V DC into your SMC (which handles power) that only takes 3 volts. (It's also very inexpensive).
It's not a complex fix, but it is detailed as you do have to remove the logic board. iFixit.com has an excellent step-by-step walk through on how to do this.  However, if this is not your cup-of-tea, I advise taking it in.
That said...you should be backing up on a regular basis.