A few years ago a 737 lost Hydraulic System A during approach, and found themselves at 1500 AGL with flaps stuck at 15 degrees, gear down.
Are you sure??
Loss of hydraulic system A would result in the gear being stuck down, but the flaps are driven from hydraulic system B, so there should have been no issues with them.
The brakes also quickly failed
Are you sure??
Normal brakes on a B737 are on B system hydraulics, so there is no reason for the brakes to have failed.
As for why the crew didn't continue to land, at the moment only they know that, no point speculating, we weren't there. There are of course many reasons, a couple that immediately spring to mind are :- if the engine malfunction occurred during the approach perhaps the stability of the approach was in doubt, it's not an easy manoeuvre to fly even when you are expecting it in the sim, let alone out of the blue, or perhaps the GA was initiated for another reason and the engine gave out during the power application for whatever reason.
All will become apparent in good time.