Oh no! I'm so sorry.
Where did you buy it? Could you bring it back there or was it a mail order purchase? I don't think leaving it in standby would do that. I've done that with both the 300 & 350 with no issues.
Do you have an AC non-USB charger? I use the charger that came with my Blackberry. Do you have access to something like that? Can you call Sony support? Have you looked at their site for suggestions on what to do?