As one, there is a fair amount of training that is specific to the job, depending on what you are doing. If you are front line it means you are a glorified pump jockey, as part of the job is fuel, cleaning and polishing panels. The rest is black box changer, you diagnose the fault to a box, swap with a service exchange spare and test it cleared the fault, then paperwork and more paperwork to sign off, and send the box in for repair. Depending where you are this can involve a lot of odd hours of work, and keeping to a schedule that is not yours to set.
If you work at the repair side you get a lot of boxes with assorted and often hilarious fault descriptions on the paperwork. Then you confirm the fault, fix it and check it still conforms to spec, and implement any mods that have been approved by the OEM for it, and that have been approved by an international regulatory body or the local regulatory body. then they are tested and sent to a store for use on the next aircraft. Pretty much every unit is repaired, even if it means that the only original parts left are a serial number label.
You have to remember that peoples lives depend on your repairs, there is a nasty feeling when a plane goes down and you __KNOW__ that you were the one that worked on that plane, or that you did work on parts that went into it. Not a good feeling, especially when I saw it happen. Luckily the pilot did eventually decide, when he looked up, and saw from his 30 degree nose up best glide angle that the trees were now above the canopy, that now was a good time to pull the yellow and black striped handle between his legs and kiss the plane bye. He cut it close, he felt the plane hit just before the seat and him left, and he landed just behind the fire.
Best fault I ever got was the following " First bomb fell on target". I just had to phone and ask, especially as I did know the pilot from seeing him around. Good pilot, still flying a fighter when the rest of his class were bus drivers of flying mahogony bombers. Big guy too, had to take the seat to full lift to get in or out, like me when working in the cockpit. How he fitted the golf clubs in as well........
BTW there is a big difference in the skills and training for this, depending on the job. You normally do a 3 year apprenticeship before getting the initial qualifications. This then gets extended as you qualify for extra tasks and well described repairs you are allowed to do and sign off. You take a long time before you get your inspectors number and are allowed to sign off the work without having a more experienced person checking that you have done it to spec and to their satisfaction. After that you then are responsible for your work, and for the work of those under you.