Laser Problem With Install

I recently had a Matrix Inifinity installed in my V7 PS2. Before I sent unit it played DVD-R Movies that had been backup movies. I received unit back quickly and I tried DVD+R backups of PS2 games and it wouldn't load. I emailed tech who installed chip and he told me to try DVD-R for PS2 backups. After I did this, the Def Jam game loaded fine. About 30 minutes into the game, it started freezing and taking long to load. I thought it was a media problem or burning speed problem, however, I started hearing scratching noises and I opened up tray and disc was scratched. I even tried original games I own and it started scratching those discs also. Like I mentioned before, I have had unit for 2 1/2 years and never had that problem until I got PS2 back from modder. I contacted him and he told me that it had something to do with laser alignment and the only time discs scratch are if the unit got dropped. To me this sounds like something that happened during an install. I'm not a modder so I don't know, but can someone give me some insight into this? I was really looking forward to this chip and all seemed well for about 30 minutes. Any advice is welcome.