Plants vs Zombies - stops working after START button pressed

That will more than likely be your issue. That sounds like "laser burn" to me, & can be caused by the disc not being seated in the tray properly. It is possible for it to be repaired. Game (or other retailers) can try & repair it for a nominal fee (less than £5), & I can attest that the process is very effective as my son has done this to several discs. Also, be wary when buying pre-owned games, as retailers have attempted to sell me a burnt disc in the past. Visually check the disc at the point of sale. Tiny scratches are fine but any large scratches or burn rings are not. Another option is for you to return your disc & buy the digital download from XBOX Live. PVZ GW is currently on offer at £8.49. But I would suggest that you read all the other topics on the issues with this game & particularly the EA servers before you spend any more of your money.