If someone wants to repair their phone, tablet, or laptop, then by all means. The only one on that list that I will attempt is a laptop. The others are just way too small. This extends to all sorts of products.
Cars and trucks for instance. If the manufacturer could get away with it, they would weld the hood shut. Certain high-end European made vehicles have special access controls in the computer. If someone not authorized goes poking in there, it will alert someone at the manufacturer and you will get a CALL telling you to get out of it. Things like injector timing and such which are used by modders to retune vehicles.
Believe it or not, forklifts have an interesting problem too. The computer has a kill bit that gets set after something like 10,000 hours of use. After that, you have to replace the computer. But the computer is no longer available, so you have to buy a new forklift for US $1500-$4000 or more.
Biting the hand that feeds IT
