Need 240V in the shop, is it already in this OLD panel box?

My brother-in-law tapped into our breaker box where the power lines connect from the street to do some welding in the backyard. A couple of years later, some of the lights/sockets started acting up (on again/off again). We found this main burned up wire. Don't know whether to blame him or if the problem arose from some other defect/problem/installation/act of God.

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