Unfortunately, you can't cash the check made out to your parents now that they are deceased"”even if you were named as the agent in their powers of attorney, and even
if those powers went into effect during their lifetimes.
The money is now officially part of their estate, and in one optimistic sense, you are freed from the responsibility of dealing with it.
So while it seems like a lot of rigmarole to go through for such a relatively small amount, you should simply give or mail the check to your brother, if he's been named executor in your parents' wills.
And if the electric company check is a refund for overpayment for services let me just add a bit of marvel: Most utility companies must be begged and begged again for such refunds.