2005 Prius Issue

Hello all,

Yesterday morning while leaving for work, I started the car as normal and the gas gauge only showed one box and it was blinking which indicated I was low on gas even though I knew I had approx 3/4 of a tank. While pondering what could have happened, I noticed the clock was set to 1:00. After less than a minute my gas gauge showed the correct amount of gas. Everything else appeared normal so off to work I went with no issues. When leaving work last night the car was completely dead.....no lights on the dash...nothing. I was able to jump start it and was able to drive home without any issues. Once I turned it off at home, it was again dead. I have replaced the 12v alternate battery once before approx 2 years ago. I will not be able to check it further until I get home from work this evening. (I got to work with a friend) Looking for suggestions on what to check first.

Thanks for your input