Third gen engine coolant bleed bolt or coolant temp sensor??

I'm still trying to fix my prius over heating / blown heat gasket problems. I replaced radiator, water pump and thermostat. Yesterday, I drove it for 6 hours freeway uphill, down hill and some local roads and finally it leaked coolant and over heated. I will need to find out where the leak is. Maybe water pump or radiator. I used a non-brand water pump. The coolant leak only happened after 199 F. Or maybe over heating blown the head gasket again LOL!! But anyways, I may need to use bar's leak again but I will pour it in from the heater hose and only let it run until temp reach 170. I also want to bleed air out too. I saw another post about removing coolant temp sensor mentioned by Mendel and Sergey K. I think Mendel called it "engine coolant bleed bolt". I took some photos. Should I just turn the white cap to release air or that sensor on the left is the coolant temp sensor?

I read that Sergey solved his over heating problem by removing that thing while bleed air. So which thing? Turn white cap / blot or that thing on the left ?

Photos

 

i will provide update later but I think the best bet is only drive it for 1 hour MAX and needs to stop for 30min before it drives again. This is what needs to be followed after blown head gasket even after using head sealant. It is a temp fix not a long term perm fix. It only works under certain condition. Pouring the sealant from the heater hose seem to work better because it doesn't go to radiator under 172 F. I will rinse the heater hose after sealant application too.

 

updates: Head Gasket has been sealed but water pump stopped working a few days ago. I saw temp went to to 240 for a few seconds and then dropped back down to 230, 220 and then 200, 195. It should be this high. However the car still runs and no engine codes. Today I put it on maintenance mode and temp also went up rather quickly but no white smoke, no codes and everything seems normal. I put my hands on the heater hoses, they are all cool not even warm and felt like nothing running in it too. So now I know the water pump maybe the cause. I bought those non ASIN brand from eBay for cheap and thinking that this should give me 6 months to get through the chip shortage LOL!!! NO.

I think it was all my mistakes anyways. The eBay water pump was running fine and I put everything back together and test drove it on local roads for almost 2 weeks already before I got on a 200 miles road trip on freeway a few days ago. It over heated and I immediately exited and inspected it. The lower hose of the coolant expansion tank below off and all coolant leaked out. WHY? It was my mistake. I did NOT clamp those hoses back up. The upper hose of the exp tank was not clamped either. But I clamp it all back up and then bought another gal of coolant from O' reilly and put it in. I was able to finish that 200 miles trip and back. However, it over heated again for about 1 min when I was only 15 miles away from home. It dropped back down to 230 and I exited the freeway and drove local roads and it stayed around 195 until I got home. Yesterday I only drove locals too but it also over heated so I know something is wrong but I eliminated the head gasket problem because no white smoke and no coolant loss and no codes. I have seen some youtube vids showing that there is no water pump code if the center pole is spinning but the propeller is not. The computer thinks its still running so NO codes. I think that is what happened to mine and both heater hoses are cool so now I know the coolant is not flowing. I will get a new ASIN pump then.