there r 2 or more options.
1. asked someone else to fix it. then u can go to the court and seek the cost of substituition work.
or 2. go to the court right away and file complaint for damages by that bastard.
You need prepare:
1. the written contract
2. proof of the breach -- shaky condition of flashing.
3. if there is a term purporting release his duty or prohibiting suit for breach, then you can alos sued based on the contract and argue for it's a standardized K and unconcsionability.
since the contract price is above $500, u can't sue him on the small claim court.
still a lot....talk to a lawyer!