PLEASE HELP! Soft-bricked

So I bought this HTC One M7, the guy claims its soft bricked and hes not able to fix it because hes technically challenged. So I take it home boot it up, its stuck in a boot loop so I boot it into fastboot the bootloader is locked so I try to connect it to adb, no luck, there is no driver on this internet that I have found that will connect to adb. So I resort to fastboot, I "fastboot devices" and sure enough it connects (wicked), first I try to flash recovery, I try to boot recovery, I tried to update zip, no luck in flashing anything because I either get a signature fail or a "remote: not allowed" then I realize my bootloader is locked, I try to unlock it "fastboot oem unlock" and of course I get a "INFO [ERR] command error". I also tried to change my cid to 11111111 and no luck. I have actually tried everything I can think of I cant get s-off to work my recovery is stock as well so theres no possibility of OTG cable plus a usb. My fastboot will not flash anything in fastboot, I cant push any files to the phone, I cant connect to adb, I cant use my recovery. So what in the actual can I do? I think i'm f**ked.

Thank you in advance for anything you can help me with.