P0A94 error code

Newbie here. My 59 plate (2010 model, 167,000 miles) has died and the display has lit up like an xmas tree. unable to start unless I attach a booster pack. message on dashboard as well saying check hybrid system.

I want to get it fixed, but am unsure about what to do - do I risk the bill from Toyota or try an independent specialist? I am also unsure how 'major' the issue is. The error code from the breakdown company is attached.

Thanks in advance for anyone who is able to try and assist me.