My desktop swiched off due to a circuit breaker trip, while busy I was playing an online game. I am disputing the websites activity logs they provide. I need log information with time stamps to prove to them that there was no active session from my browser.

The website admin staff are stating I continued my session after a certian time but I know for a fact I didnt. I can only find when the session started but cant find when it ended (When my power tripped). Please help