No power to my garage dead wire?

I had a cousin who knows wiring and boxes come out and trouble shoot a circuit down in my house that seemed to happen when someone plugged in a power tool. My garage has no power. He determined that the main wire coming into our garage was burnt out, the wire! He tested this by using a cut plug and splicing it with some three wire and putting that into the second wire in the circuit (where we had the load in our outlet) and bringing wire over to the outer side of the circut. When he plugged it in and turned on the power the rest of the garage worked. He said two ways to fix this, one is to have a new main wire run through the house all the way to the garage. Second by bumping up our washer and dryer from 20 to 30 and then teeing in that main line to that circuit in the garage which is almost in the same wall (3 feet away). What do you guys think?