Mobile network problem

Hello. I've been using BlackBerry Bold 9900 for over 2 months already and it was all good until now. Two days ago my battery 'died' and BB didn't want to turn on but after several tries (pulling battery out, charging with battery out and then putting it back into my device and stuff) I've managed to turn it on. However, after recharging my BB to 100%, I can't turn mobile network on (Wi-Fi works fine). The 'check' mark turns grey for a while and then it disappears like it was turned off. I've tried with three different SIM cards and it still won't work. The only thing that comes to my mind is that before my battery died, mobile network was automatically shut down (as it always happens), so my guess is that it is somehow bugged and despite recharging the battery it still reads it like it was drained. Any suggestions?

Regards,
Candaar

Hello, well if you still have the issue, I would recommend try reloading the OS. I don't really know what could have gone wrong, but I wanted to help. Luck!

Thanks for the first response!

However, I've tried to wipe out and install the newest OS and the issue is still present. I'd like to see some other ideas! :)