Bungrudi
Since you speak of a bird produced back in 2015, I think it's likely you have to deal with a jewel (if it functions flawlessly of course).
To explain: DJI has made at least three P3P models, that were licensed at FCC, the best one being the one named W323 (not W323A or B etc). W323 has the maximum RF power (means range) and is having this FCC ID: SS3-WM3231503. Is your AC having this one ? (may be found on the AC right-side label along to the big lettered CE1313)
Later on (2016) I've noticed DJI has placed on the market also less powered models, with FCC ID: SS3-WM3231507 that has -18% RF power compared with the '1503' model, and another one with FCC ID: SS3-WM3231510, that has -28% RF power compared with the reference '1503'.
The same in terms of RF power applies for the RC. DJI has licensed to FCC three models GL300A, B & C. A&B have the same high RF power, while C is less powered. Since you state the bargain AC comes with the RC GL300A, means you have the best RC DJI made for the P3P/A models.
About the batteries. Both are ok from the charge cycle number point of view, 24 it's like a new unit, while 42 cycles isn't crap at all. I have a battery that has 58 cycles and still has 4000 mAh (90% of a new one).
True, you have to deal with the shell and its cracks, but
@dan84uk has given you the solution by epoxy-ing them from inside. If money isn't an issue, buy a new shell as
@msinger has suggested.
Opening the shell is a nightmare, because you have to take a lot of care not do damage anything inside, but Dan has shared to all of us a true revelation with this video "opening the shell in 60 sec"
But before all these, you have to make sure the whole suit is functioning, so it's worth investing in it further. Start the motors. Listen them, they should run in a smooth manner.
Take-off and hover at 5-6 m. The bird shouldn't "walz* around the given point, but stay "as hooked" in the sky. Stay here minutes and make sure all is ok. In open field the bird should see at least 15 satellites. Check the compass mod figure (it should be in this span 1400-1600)
Check if it records HD/2.7k/4k video well, rotate the AC rapidly in the air left-right, it shouldn't get some video artefacts, macroblocks a.s.o.
Make sure you have a solid phone/tablet, it would be a pitty to conclude wrongly about the bird, but the root cause is actually the device which runs the GO app.
By sure, other experienced folks here present, might offer their know-how too in terms of evaluating the suite.
Tell us how is going.