I received an late '06 2.16GB Core 2 Duo 1TB HDD (upgraded) 4GB RAM MacBook Pro. Now, it will not boot off the battery. But once it is connected to the power cord, it will boot. I can also immediately remove the cable and it will continue to boot from the battery. So, it will most definitely run from the battery. The software however, shows the X symbol along with 'No batteries installed'. System profiler gives the same info and coconut battery says nothing is in there as well. The MacBook Pro also does not charge the battery, so it will run out and the MagSafe connector keeps it's green light at all times. I tried resetting PRAM and SMC and PMU as well.. but to no avail. Anyone knows what can be the problem? It runs when booted on the battery when disconnected from the AC.. Also, I tried a brand new battery as well. So I tried 2.