I correctly installed a new OEM serpentine belt on my 2008 sport manual Fit last week. I ran the engine and snugged down the adjustment bracket bolts (A + B).
Then I got confident....and ONLY used the tension adjustment bolt (BOLT C) when adjusting tension (a few adjustments when the belt slipped on cold startup each morning for 3 days, usually 1-1.5turns of the adjustment bolt C) which resulted in a belt tensioner bolt and (i assume) a bent tensioner.

I am NOW hearing a whirring sound now from the tensioner bolt & alternator & idler pulley area. My wife said she smelt a faint burning sound which I assumed was the belt.

I have loosed the belt as much as I can now but the belt slips when revved and I imagine will slip on cold startup.

I assumed that the bent bracket has misaligned the alternator which is causing the whirring noise. TURNS OUT THAT BY OVERTIGHTENING THE TENSION BOLT I KILLED THE BEARING IN MY IDLER PULLEY. See post below...

 

I did the same when the pivot bolt C on my Miata was impossible to loosen, but I managed to tighten the belt just a bit without damaging anything. 1.5 turns several times was probably too much

When I replaced the alternator on the GD, taking off the bracket was pretty easy, it's literally just undo bolts A+C.

 

The bracket is attached to the engine timing cover by two 12 mm bolts
I broke loose both of them (1/2 turn) as well as bolt A plus, of course, the bolt B.
now you need to find a good used bracket and bolt C
most likely it got bent either because bolt B was not loose enough or the bracket channel had a dent or rust causing jamming of adjustment nut

 

UPDATE: my bent bracket will stay on the car since it was not the source of my noise. My issue turned out to be an Idler Pulley bearing that died (after I put too much tension while tightening the serpentine belt).

If your serpentine is old then your pulleys are too. Check them carefully before and during changing the serpentine belt. I used the long screwdriver listening technique to listen before removing the belt. then I removed the belt and could freely spin the pulley. Then once the pulley was removed it spun way way too easily and showed grease&dust on the outside which means the seals are compromised.
Replaced with a DuraLast 231148 which is a tiny bit larger and wider than the OEM Honda pulley. Had to use 2 washers between the bearing cover and pulley so the cover didn't rub. Car is silent again.