Dead phone after one successful power on?

Hi!

I have been working on a Pixel XL, to replace the following:

• Battery
• Daughter Board
• Screen

Initially, I just needed to replace a faulty daughterboard because it broke by corrosion. I took the opportunity to change an aging battery and broke my already cracked screen during disassembly.

Anyway, I put all the pieces together and turn the phone on. Hurray, my phone is alive! But it wasn’t booting properly it seemed. It stayed on the screen with the animated loader for more than 5 minutes. So I decided to force turn it off. And since then, nothing. I can’t even turn it back on. I unplugged/replugged the battery (I haven’t resealed the phone yet). The charging light doesn’t blink anymore. But the motherboard gets warm when I plug the phone.

What could be happening ? How can I investigate more? Thanks!