they are a 1500mah 15a continuous cell. and probably old age and an application that dumps them in about 5 minutes.
i would replace with these.
those are my go to for tool pack rebuilds.
just rebuilt some...
i have rebuilt a bunch of bikes myself.
got a goldwing tore down right now.
getting that tank fixed is first.
as long as its shedding crud you wont keep a carb working very long.
i tear the carb down and remove any plastic.
then soak in hydro seal or berrymans carb dip.
blast it out with air...
enough energy to blast that diode=dead driver opto.
and likely other parts.
on high cost parts jobs i replace everything.
then test via dim bulb.
idea is to have enough resistance in circuit to limit current if something gets latched up .
a bulb does that and serves as an indicator.
got one of those chinese componant testers?
since you have several identical channels grab the diode from either side.
the tester will tell you if its a plain diode or a zener.
the ic behind it is likely an optocoupler and bad too.
any part on the gate of a failed fet is suspect.
and if you dont...
can you see whos cells are in these?
all the real ryobi packs i have seen had samsung or lg.
had 1 knockoff that had generic 2200mah laptop grade cells.
they must have thought that in 3p they could get away with it.
they were beat.
many cheap and nasty ups units have a timer in firmware.
its not designed to run beyond its stock battery capacity.
best ones are the old metal case apc and best power units.
i usually set up a fan that runs from the logic so it runs in inverter mode only.
metal case= probably good.
file a SNAD.
significantly not as described claim.
the return shipping is on the seller if they do not come to a reasonable solution.
iof you did buy on ebay and used paypal you are in position to get a settlement.
those are closer to a 17670.
see if they still have good capacity.
i have some in a old outhouse light i keep charged with solar.
they have been good now for 7 years.
nothing fancy to use them either.just a blocking diode.
3 cells inside the light and a 500ma 5v panel.
if you get stuff like i do...
thats an old group regulated design.
it should have a load on +12 too.
if you have a bunch of the chargers that run from +12 you can run them from this unit too.
and your unit is from the era of bad capacitors.
it might need new ones.