These hardened cysts usually do not "pop." They are usually a hard, waxy material (probably cholesterol and oils) that won't easily drain. That's why doctors usually cut them out, but unfortunately, they take the hair follicles with the cyst so you end up with scarring and thin or bald spots where the cyst was. :(
Yes it will pop if you stick it with a pin and you could also cause a serious infection that way. See a physician who will agree to drain it or remove it under sterile conditions. It is not harmful, just caused by the oil in your scalp. It can be done with a local and in a matter of minutes. They wouldnt even have to put you to sleep, they can just numb the area. DO NOT POP IT YOURSELF!!! You don't want to get a staph infection do you?
I don't think using a pin is a good idea. I had one of these and hot compress did help.
Some times it doesn't go away and the doctor might give you antibiotics and the next stage is surgery.
Please dont' neglect thinking its a small thing. It might get very infectious and hurt u bad.
Do the hot compresses and try bathing in oat milk.
The heat might help, it would be worth a try, but, if it doesn't let the physician do the removing, that way, you will be in a sterile environment and it will be done properly.