what went wrong with my hatch?

[serprise]

I put a dozen eggs in my homemade bator (first time using it) and it stayed between 100.8-101.5F. The humidity day 1-18 would range from about 28-35%. Day 18 when I went to add another dish for more surface area to increase humidity I noticed I already had a pip (on narrow end of egg

) with a baby chirping at me while in there. I immediately closed it as soon as I got the dish+ rag added and humidity maintained between 58-62%. Within 12 hours there was 2 more pips. After about 30 hours total I noticed the first one (the backwards one) died in its egg, one was very faint and I know I shouldn't have helped it but I did and it had spraddle leg which I performed first aid on before I went to bed and it was dead by morning. The 3rd I don't think needed help, it was very lively but I was there and seeing the other 2 couldn't get through the shell/membranes I went ahead and helped it a bit, it's alive and well. The other 6 eggs (other 3 stopped developing around day 8-9) aren't moving or anything and while it's day 20, it's been over 48 hours from the first pip and over 36 hours from the last pip.
I read 101F is the perfect temp and I had it bouncing right around there with less than a 1 degree fluctuation. This is an incubator I made out of one of the styrofoam coolers, a pc fan and hot water heater thermostat. The early hatch makes me think high temps but unless both my thermometers are wrong my temps should be spot on for the eggs. The eggs that are still in there look as if they stopped development late, there's no light that passes through other than through the large air sacks. I still have them in the incubator since technically it hasn't actually been 21 days yet but I'm guessing since others in the same environment hatched over 48 hours ago it'd be wise to not get my hopes up.
These are black copper marans eggs in case it matters. If you can give me pointers for next time that might help my success I'm all ears. I'm new to raising chickens and have no experience incubating, I just followed some directions I found and I did succeed, just not as much as I was hoping. Now I'm gonna have to go buy some chicks so the lone chick has some friends

 

[gimmie birdies]

I had my homemade bators and had good success until winter hit- then the heat would flux too much and I had a harder time- it is warming up again so I am in the mitst of a hatch.

Did you have good air holes? I dry hatch, but when I had hatched in foam bators seems the less water I used the better. I would just keep trying. Good luck to you.