Default Noob Help Please!!

So yeah I dont really know crap about most things, so I need help to prevent me from having to buy a new phone.

So a few days back my XT907M got the new 4.4.2 update. It worked fine for a couple days then it went into a boot loop. It had done this a few weeks before the update but it snapped out of it somehow.

It will not let me go into recovery mode, but I could get it to go into fastboot, so I did some googling and decided to try my hand at reflashing it. I had trouble getting my PC to verify a connection to the phone. I tried getting different drivers, but again i dont know what the hell im doing so i had not luck.

I took the phone to a place called World of Wireless here in Minneapolis to see if they could fix it. They told me that they went in and deleted two bad lines of code, but since the new fastboot files arent available for 4.4.2 that there was nothing they could do because the phone will not let them go backwards.

is there anything I can do, or am I just going to have to buy a new phone?

Sorry if I posted this in the wrong place.