On a 2000s-era opener, the job starts with the safety sensors at the bottom of the track, since misalignment there is the single most common reason a door won't close on command. After that we check the logic board, the drive gear, and the belt or chain tension, in that order. Most of these units are old enough now, roughly two decades, that the circuit board is the part most likely to fail outright rather than wear gradually, and board failures don't give much warning.
Parts availability is the one honest limitation here. Some board and sensor models from that era are discontinued, and we may need to source a compatible replacement rather than an exact match, which can add a day or two versus a same-day fix. We'll tell you up front if that's the case rather than promise a part we don't have in the truck.