If it is not chiming, it means it is not passing POST checks. Try booting it with the battery disconnected. It most likely is the logic board signal ppvcore_s0_cpu, so check that out as well if you have a multimeter (you will need to get a board view and schematic for 820-3115).
Most likely is a logic board issue, possibly dead CPU or voltage leading to the CPU? Check the board for liquid damage as well, and clean if it is present (but note the areas effected).