Akura Retro Phono n BT Player AITVS550 BTRB

Hi have been given a couple of Akura Retro Phono n BT Players and of course they don't work, where do I start to test voltages etc on it, getting 5vdc out of transformer and to the board, the battery is giving out 3.7vdc , don't realy know where to test for any voltages , tried to find a schematic etc for it, but no luck up to now.
Spike

Exactly the same has these

New

IC's as in order left to right as per pic uploaded:
1st: top 28pin, BK3254SS28B
2nd: top 8pin, HT135T
1st: bottom 6pin, B6286T
2nd: bottom 16pin, YD3412

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On one of them the charging light comes on and a blue ( bluetooth ) led comes on then blinks and I can connect my phone to it, but then after a short time it goes off and only the charging light remains on, but no activity with the turntable motor activating !.
on the other one no lights come on .

cheers
Spike

New

Found the same burnt out chip on both boards .
4054, Standalone Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT

spike

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