Android Security/Reinstalling Android

[Exploration]

Okay so i've had a notion to fix a rather good tablet i bought a while ago and wondered if anyone could help. Basically it came Pre-installed with Kaspersky (Yep, bad news already). On attempting to remove it the thing locked me out saying it needed my password entered on a specific account. Of course i never made one and it didn't tell me what the key is to unlock it anywhere even in the manufacturers manual. So to recap i can get to the lock screen where it asks for a digit code but i can't unlock it as i don't know what that is.

So that's fine, i thought, i'd simply enter recovery mode like all my android stuff in the past and reset it to factory. BUT here is my problem, no matter the key combination, the anti theft thing seems to have locked me out of that too because the factory reset procedure listed the buttons i press to enter recovery mode and it doesn't work, i later confirmed this online it's actually a common thing. But i don't have any details/register stuff relating to the anti theft by Kaspersky. I find it a bit of a twat move to lock me out of £100s of device which 'I' paid for but whatever.

Anyone have any ideas on how to reinstall the firmware/android onto this device from a computer and connecting the tablet to the PC or some method of revealing the password?. It has Android 4.3 or 4.5 i believe.