Not booting after battery replacement

After replacing the battery in my surface pro 7 I can't get it to boot up.

The surface functioned fine before the swap, the battery just couldn't hold a charge for more than an hour and I needed it to last longer.

Since the repair,

Occasionally after pressing the power button the windows logo will appear for less than a second and the camera indicator led will blink but that's all I can get it to do.

The red led on the motherboard that indicates the board has power is on.

I have tried swapping back to the old battery and get the same result. I have also tried running it with no battery plugged in just the charging cable and still get the same result.

I have left it charging now for 24 hours plus and still the same.

Replacing the mother board is not an option as my main goal now is to get files off the SSD which is soldered on this model. (Yes I know I should have backed them up before doing the repair.)