Locked out of CRT

There's an old CRT that a buddy found laying about. No case, just the screen and the PSB connected. We hooked it up and the thing ran well, no signs of damage or any visible modifications. No parental lock.

After a bit of poking around in the menu, we came across an option under "Parental Lock". Don't remember what the name of it was, but it was some sort of lock and on the "off" position. After turning it on, we lost control of the tv. We tried turning if off, but now can't turn it back on.

So the question is. Seeing as we don't know what brand it is, or the full name of the setting we poked at, is there a way to turn the thing back on?