Many years ago when Dell was getting started. My company contracted to do 3 third party service on their business computers. Parts were always overnighted to the customer and we were to just install them. We were not allowed to troubleshoot. Only change parts that 9 out of ten times didn't fix it. Best part is when they would send out a blank HDD with instructions for us to reinstall the OEM OS which we didn't have. The whole thing an absolute cluster. Dell making promises we couldn't keep and our upper management *****ing that we were spending too much time on Dell stuff and not OUR customers. After a year they finally terminated the Dell contract.
We asked Dell why we were not allowed to troubleshoot their PCs they said we weren't qualified. We had to laugh because we had been maintaining high end windows and linux based print servers and our own PCs for years. Can't fix corporate stupid.