Found the problem...(cell culture)

I've been struggling with HepG2 cell culture since joining the lab 2.5 years ago.

My cells were growing slowly and were acting cranky. After 1 year we discovered the senior lab member trained me incorrectly on caring for this cell line. Because they were growing slowly, I would passage them once a week. With the last cell line if the confluency was too low to split, I would still trypsonize and replace all the cells. He said no don't do that, just leave them be and he put away my media. I asked to confirm I didnt have to at least change the media or add more. I trusted his experiences and advice over ATCC (big mistake, huge) and was only changing the media once a week.

Fast forward to now, due to MANY OTHER ISSUES WITH THIS MAN, he's been moved to another lab (he should be fired). Me and PI had thawed 4 sets of HepG2 cells either stably overespressing empty vector or a protein. They're slower growing and more sensitive than our usual HepG2 cells. They kept dying. We co-parented the shit out of those cells and they all died except two flasks that were barely hanging on. We troubleshooted starting with the media all the way to the biosafety cabinet and incubator.

2.5 years later we made an important discovery. The incubator, while the display read 37C, the true temperature read by a glass thermometer was 40C. When I joined the lab this person replaced the temperature probe and never calibrated the sensor. I was the only person who used this incubator and spent most of my troubleshooting on what I could be doing wrong. Before any experiment I do from now on I will have to 1) check all the reagents to make sure there's something in there and it's not just an empty container and 2) pretend every machine I'm working with is new and fresh out if the box and reset it up myself.

I have a chemistry background and joined a lipid cell signaling lab, and was very clear with my PI I needed training but I was up for the challenge. I was assured the two scientists in my lab (both who have completed a post doc and were older) would be there to train me on all the protocols that had been established in the lab so I wouldn't have to reinvent the wheel. This stupid dumb guy literally screwed up training me, and kept touching my experiments because he wanted to help until he was transfered (even after he was told to not help me at all he would stand over me and make suggestions until I either finished the experiment my way or gave in and did it his way - it was so annoying I usually caved).

I'm tired. I have no results so far. I'm a little paranoid tbh. My remaining flasks, one of each overexpressor type, are in another labs incubator. One doubled overnight, the other is at least not looking any worse. I was getting demotivated that my experiments weren't working, then even moreso that now I couldnt even keep cells alive PERIOD. It wasn't me. My PI is explaining to my committee before my progress meeting what we are starting over and why. So there's that.