After fixing corrotion damage the unit stays dead, no current absorbed

I've got this junk Game Boy Advance, seller told me it won't power on.

The unit was suffering some corrotion and the battery contacts were gone. I replaced them with some parts from Aliexpress and I soldered. I then checked the ohmic contact between these parts and the power switch, and they are ok.

I finally cleaned up the board and checked for leaking capacitors, found no one. To my sight, there are no other signs of corrotion or damage elsehere in the PDB (I can provide some photos ofc).

I reassembled and I was largely optimistic, I must admit.

I connected to my bench powersupply and...nothing. The unit stays dead. And it absorbes 0 A, which is probably no good.

The question is: where and how have I to go to deeper testing the unit and where are the most common pitfalls, with the abovementioned symptoms?

tnx allot for your support!