If the janoel 10 is anything like the janoel 12, you definitely can’t trust the built in thermometer. I’ve got 2 of the 12s and they read very differently from each other and from my additional thermometers that I calibrated and put in there. It’s not going to help you with this hatch but it’s a very good idea to get one - a lot of us on here use the ones with a probe meant for reptiles, which usually are cheap and relatively easy to calibrate.
it’s difficult to see in still images and even to compare what you’re seeing to pictures you find as reference when candling eggs. Generally I don’t look too hard for veins that late in the game either because a lot of the time the egg is too full. If you see movement or fluttering against the air cell, or even feel the chick moving in there when you pick it up, it’s alive. If it doesn’t smell bad or having nasty things oozing out of it, cross your fingers and proceed with lockdown as expected. And then wait. And wait.