New (to me) 1st gen roomba resurrection?

Hi, I've just acquired a 1st gen roomba off of craigslist. The women I got it from swore it worked when she last used it, but hasn't used it in quite some time. I have found the instructions for 'resetting' the battery, and am about 6 hours into a charge.

Has there historically been a problem with the power button on the 1st gen roombas? I can't seen to get it to power on , even plugged in. Or should I just wait until the 18-24 hour mark and see if it's charged?

Thanks in advance!
A new Roomba/iRobot user and hopeful enthusiast.

Rich