Hey Afro,
Honestly i've found the best is to assist feed them, BHPs can go a couple of months easily after hatching without eating so you can wait a bit longer and they will probably start on their own.
The way i assist feed hatchling BHPs is with a pup rat and something like a credit card, a liminated card like a library card without any numbers on it.
Put the card in their mouth and slide the rat pup in on top of it. Get the rat pup down into the troat abit and then take the card out.
It can take a bit of practise to get it right but i find it works great, it normally only takes one or 2 of those and they start feeding on their own.
The other good way is to use Geckos as scent, they really love geckos, i prefer not to scent because it takes longer to get them onto unscented.
Best of luck.