T480 won't boot - power button just flashes.

[kae2020]

I bought a T480 and everything worked. I disabled the internal battery in the BIOS and then upgraded the ram, ssd, and cpu fan. It doesn't have an internal battery. I bought a 4K screen and new cable for it but put the old screen back in and reattached the old cable because the new screen doesn’t have brackets on it and I didn’t want to tape it in place at the time. When I powered it up it wouldn’t come on. Nothing was displayed on the screen.

I put the old ram and ssd back in and tried powering it up and got the same thing. Nothing was displayed on the screen. The power button would light up and flash 3 times. The third flash seemed a little longer than the first 2. After about 5 seconds it would do it again, etc.

I thought maybe I corrupted the BIOS somehow so I reflashed it with a copy I got from post #206 here:

https://www.badcaps.net/forum/troublesh ... ost3754498

It didn’t help.

I’ve tried the emergency button on the button, installing just 1 ram stick in either slot, held the power button down for 30 seconds to make sure it was totally dead, and checked all of the connections. Still nothing.

What did I do to it? I can’t think of anything I did wrong. After reading some posts here maybe the LCD cable is the problem?

Also, if anyone can point me to brackets that screw in to hold the new screen in place, that would be great. I know if I try to tape it in place I’ll screw it up.

Thanks for all of you help!

[axur-delmeria]

One question: did you connect the charger to the laptop at any point after reassembling the laptop? It wasn't mentioned so I just want to make sure.

[kae2020]

Yes. when I put the laptop back together I plugged the charger in and the battery was left out.