Overcharged my mini split

I am installing a new Pioneer 9K mini split and had a line break and lost all the freon. I was sent recharge kits. The specs called for 28 oz 410a. I put one can in the system (28oz) and my pressures were around 90psi. So, I went ahead an put most of a second can another 28 oz in the system. 30 minutes later, I checked my pressures and now I am in the RED. I tried to open the valve to release some pressure but it did not seem to come down.

I shut the system down. Question?

1. How do I properly measure the pressure. Do I turn it on, set to max temp and wait a while? I must have not waited long enough the first time and kept add freon.

2. When I let out the freon and the pressure still show a high rating, does that mean I need to shut it down and let it cool off?

3. How is the best way to get the excess freon out?

Thanks,

source https://hvac-talk.com/vbb/threads/2228645-Overcharged-my-mini-split?goto=newpost