3GS - No power - triggers USB device drawing too much power

I've a 3GS that had been disassembled some time ago to replace a broken screen. Owner panicked and left it in a drawer in bits. Passed to me to see if I could restore it to working order.

The volume key ribbon cable was torn and volume keys were missing so I ordered replacements. Also ordered replacement battery as that was missing. Re-assembled but when it's plugged into USB it trips the 'drawing too much power' error on the Mac.

Checked battery and it is showing 3.7v. As I don't know what APN the original battery was I'm wondering if this could be the issue, would using a battery with the wrong APN cause this?

Anything else I can check? All the connectors are seated properly but I don't want to waste time on more parts if the issue is more deep rooted, i.e. logic board dead etc