Prius gen 2 Death triangle randomly appears

Hi Gurus,

Prius iTech 2004 (Australia)

I just did the hybrid battery reconditioning and I am pretty sure all the cells are healthy as I did a 2 min load test on each cell and then paired them correctly. However there seems to be a weird issue happening.

Issue : If I drive without cruise control or turning the aircon on, it drives perfectly no codes at all. However, If I turn on either of them, then after I drive for 10 mins it gives me death triangle and the code on OBD scanner says P0000 & P3021. And when this happens the hybrid battery fan starts running as well as Engine starts running too and fuel consumption shows 99.9L/100kms. Even if I park the car the engine still keeps running and show that fuel consumption rate.

I initially thought the inverter coolant pump is dead so I replaced it with a new one, also did the bleeding and coolant top-up. Then I thought MAF sensor could be playing up so I took it out gave it a nice clean with MAF cleaner, It didn't look dirty at all it was super clean as is. Even after this the issue still occurs.

My guess - Hybrid battery fan 'Plug' malfunction. Could it be possible? I saw on YouTube a guy mentioned even after replacing the hybrid battery with new one, the code was still flashing and then a Toyota engineer bypassed the connection of hybrid battery fan and that fixed the issue.

Attaching the Hybrid battery monitor report from Dr.Prius app while I was driving. No issues occurred as I didn't use Aircon or Cruise, but if you can look at the report and let me know if something looks suspicious.

Any help is appretiated!