The prius series 1 battery computer has 40 diodes and capacitors in an array. If one of these diode or capicators fail the computer is faulty.
If you see the tortoise icon when the battery charge level is in the green, your battery computer is faulty. You will have to get another computer. Driving with this computer will overcharge the battery and destroy it completely. I mean completely that is most of the cells will be destroyed until you can't drive it at all.
You can't even replace the battery with a new one!!! The computer have to be replaced.
It may be possible to carefully drive the vehicle but you must not let the overcharge 100% charge indicator show for too long and you must back off when you see the yellow charge indicator. It is difficult to drive within these parameters.