Why is the bud dry hard yellow and not growing

Take a photograph, or just look at it under normal lighting. I bet it is greener than you think. The color is consistent below from what i can see in the picture, so i don't think it is bleaching. PLant does look overfed in more than 1 way. You can see better in real life. If it is distinctly paler at the top, reduce light one way or another. This looks quite ripe, so you probably don't have much longer. The calyxes are fat so they can't really get any larger than what you see. Donks don't happen due to time and patience, that's a matter of genetics and methods (overcroded = smaller buds relative to genetics). Any one plant will grow X grams per sq ft. IF you have 1000 colas, that mass will merely be distributed across many more bud sites = smaller nugs. There's a happy zone for each pheno that you can only guess at until you grow it out as far as number of colas per sq ft to get good buds that are easy to trim and reduce risk of pathogens. big buds are 90% an e-peen. more trouble than they are worth.

I saw the last video you uploaded The problem is too much heat and poor lighting

if it was a light stress then the top of ur bud'd be white and leaves'd be curling like canoe also P excess has another sings don't let em to confuse u 👇

hey 👋 a cluster of buds; check that you don't have thrips under the leaves; the small dark spots could be an infestation, or even a fungal infection. If not, you have a nasty case of nutrient burn and probably heat and/or light stress. In any case, a thorough flush would be a good idea.

Could it be from light bleaching/burning? Or a heavy overdose of PK?

K excess