See if this helps:

Disconnect the power adapter from the C3500.
Remove the Battery from the C3500.
Press and hold the power button on the C3500 for 5 seconds.
Insert the battery ONLY.
Try to power up the C3500.

If this fails, remove the battery and apply the power adapter only. Then try to power up the C3500.

If that fails, try with both Battery and Power adapter.

At any rate, if/when it powers on, you should be able to resume normal battery / power adapter operation.

LK