8700g Won't Power On...

[karin1968]

Just received a 'new' battery i bought on ebay. inserted it into my 8700g and got a white back lit screen with a pic of a battery and blue thunderbolt going through it which i assume means the battery is charging. waited about an hour and the phone still won't power on so figured it needed more time... it's been about 2 hours now and just went back to check and now the phone is completely dead.. screen isn't lit, won't power on... removed the battery and the a/c cord and reinserted both and now the screen is lit as it was before [white battery/blue thunderbolt].
any ideas??