Try this. Pull the battery and the power adapter. Press the power button several times to make sure it's fully discharged. Reconnect the PS WITHOUT the battery, and see if it'll power on. If that works, power down, reinstall the battery and try to power up again.
Family Daily Drivers- T430s, T530, X220
Work- Sadly, the ThinkPads have gone away...... and replaced by HP ProDesk SFF drone machines
Other Projects- Edge 15, Z61m (Titanium)
Historic Retired ThinkPads- T42p, X20, A31p, 701c, 760XD, WorkPad C505