This symptom could be due to a number of problems. In the past, the Acer Aspire 7736Z-4809 model in particular has faced issues with dead or malfunctioning motherboards - which can lead to secondary problems with the BIOS, battery and power supply.
If this is the case then the motherboard needs to be replaced entirely. To make sure it IS your motherboard and not just the other components, check out the [[Acer Aspire 7736Z-4809 Troubleshooting#Section_There_is_Frequent_Freezing_or_Random_Shutdowns|troubleshooting guide]] for ways to diagnose the problem.