MBA - help me with the decision please

Hi guys, Sorry for the long post, I was trying to explain my situation as best as I could.

Not long ago, I bought pretty much brand new 2014 13" Macbook Air 256gb at a pawn shop, everything was great, what was even greater at that time was the price, i bought it for roughly $565 in excellent condition and with original box (all serial numbers are correct etc).

When I got it home, I was a bit surprised that from the start button, machine was starting straight to user login (no chime, no apple logo, etc, each time i would turn it off, it would start like this the same). And it has been set up on Marvericks by the pawn shop. It did have some apps installed on it including Find My Mac by the pawn shop person.

I have decided to perform a clean install of el capitan, prepared bootable USB, turned off the machine then power on while holding alt, just to be surprised and see the Firmware lock... After contacting guys at the pawn shop they provided my some 4 digits pins but none of them worked, they said that they will try to contact the original owner but that wasnt helpful as well.

I'm not new to the macs, so Ive restarted mba, and then using the terminal Ive bypassed firmware lock to make the machine power on into recovery mode, where then I wiped the whole drive, inserted el capitan usb, and choosed it as a start up disk,

it worked, ive performed clean fresh instal of el capitan, set up the machine to my own icloud account, my own FIND MY MAC account as well. It seems like everything is working except This firmware padlock, its still there.

I was digging round the mac, and by using terminal Ive mounted OSX BASE SYSTEM, in SYSTEM, ive found CDiS in which Ive found Lock.app, after opening this, ive seen the grey iCloud lock screen asking me to input 6 digits (none of the digits provided by the pawnshop worked, same with the ones provided by original owner), i turned off lock.app using task manager.

Anyway, I think this could be a big clue that the Firmware password would possibly be 6 digit icloud pin?

What should I do? Should I return the mac? keep it? Considering the bargain price?

What are the downfalls of firmware lock considering i had fresh install and have everything now under my icloud and my findmymac? Could someone still remotely access my files or use my webcam or brick the machine?

Thanks

Thanks for advice but I dont live in US :/

Any other advices?

Thanks!

Will it be remote way?

Also, what are the other disadvantages of having efi locked mac besides no access to recovery hd etc?