Did business wire my audio bad on accident, on purpose, or none at all?

Hey everyone I recently had my 1600 watt Lanzar vibe pro two-channel amplifier malfunction and break. Before this a little while ago my stock radio broke (had for years never had a problem before subs were put in) and my subs blew. A bad quality stupid business wired everything and put the amp in. I'm not to big on car audio but could they have wired it bad accidentally or on purpose because I have had a lot of trouble with my car audio so far. Also this is strange please help me with this, on the side of my front seats there are power buttons to move the seat up and back, somehow when I got my sub and amp installed the power basically quit working. I only noticed it had to do with the amp or wiring when I clipped the power wire to the amp to save battery. Since cutting the power wire the seat works like it did before I installed custom audio. Help I don't know what I need to do or if I have to rewire everything because I'm installing a new amp soon and I'm wondering if it's possible to use the old wiring and everything?