Find out whether income tax return filed

I also want to know from which assessment year has it been mandatory for a Company(Pvt Ltd.) whose turover is under 5 lacs(in other words there has been tax audit applicable ever to the company) to file returns electronically?

Also, although it is obligatory for every Company and Firm to file a return, what happens if a Company has not filed any return at all? Apart from the following:

1) Penalty u/s 271F of Rs.5000 at the discretion of the AO

2) Interest u/s 234A if tax is payable after considering TDS and Adv Tax

3) Failure to carry forward certain types of losses

Is there any other penalty which an AO can levy on a Company for failure to file return at all...