What violation of consumer protection or lawsuti would this mobile electronics installation company be facing?

If the improper installation damaged the vehicle or fixing it cost you money, then you should consider filing a claim in small claims court if the money amount is below their money limit. If it is above it, then you should talk to a Consumer Law attorney and find out what the law in your state says and how it might help you. Some claims that might fit your situation are breach of contract and warranty, negligence, and perhaps violation of your state Udap law (most of these state Udap laws make it illegal for a merchant to do anything that is deceptive in a consumer transaction). To find out what your rights are for sure you should see a local Consumer Law attorney near you. Call your local attorney bar association and ask for a referral to a Consumer Law or Contract Law attorney. But don't wait too long because your legal rights will expire if you don't file a claim quickly enough.