How to check Canon 650D/T4i before the purchase??

Can anybody please guide me (in detail) how to check the  Canon 650D/T4i at the time of its purchase.

I reside in a developing country and since there isn't any Canon Store in my area so I have to buy the dslr from a local website - ONLY 7 Days warrantee, meaning that once i have the DSLR then I will have 7 days in which I have to check the camera and the lens to see if everything is working fine or not.

So really need good advice on how to CHECK and EXAMINE the camera and its lens.

Thanks.