program/erase MAX II with TDO disabled?

You may not have 'bricked' your board. However, driving a GPIO into TDO is not the smartest thing to do - I suspect you've realised that now...

With both your GPIO output signal and TDO driving the same net, your Blaster can't make any sense of what it's receiving. You are going to have to cut the track from the GPIO pin to disconnect it from TDO. You must clearly leave the TDO track to your header intact.

Hopefully, the drive strength of the GPIO isn't enough to damage the TDO driver. Providing that's the case I'd expect your board to spring back into life.

Cheers,

Alex