Brand new bellows job for customer - both filled with seawater after 3 months?

Hi all - so I do own a one man boat repair shop and always try do the job right once! Did a bellows job for a customer end of last yr (early 90s twin cobras) - boat was oretty trashy from the outside when it came in. Brought boat back in for a checkup after 3 months - both uj bellows filled with seawater- now im trying to see how this can be-

Customer made a "comment" when I went down there - "Man am i glad you wired those bilge pumps up right!" - not sure what he meant by that one. Im tempted to say he must have somehow got the engine bay full of seawater cos I have never had a bellows leak - nevermind both after 3 months mostly sitting!

Bilge pumps were working on auto when I left. Maybe they ran the batteries down in the slip and the boat took on water -

His transom was pretty bad (noticed when torquing down plates) - however, that should not leak into the uj bellows but engine bay - only place water can get into uj bellows (according to me) is:

• Via grease tube (although highly unlikely unlikely imo - it would take at least 3-4 psi to push grease out of the way)
• Water oring blowing out and leaking past housing/bellows seal as well (very unlikely)
• Main gasket leak AND bellows/drive leak
• Marred drive surface (i always check for bumps/nicks and file down) AND bellows/drive leak
• Leak at transom hose clamp (ive never had a leak here on any boat) and they are both still very firm (i check after a day for rubber compressing)
• Leak at drive where it seals from behind in bellows v-groove (requires water oring failure and/or main gasket failure) as well -
  
  In most cases it would take 2 simultaneous failures to leak from the drive side - only other place I can think of is from the inside?

Looking forward in case I missed something here!

Thanks!

I think your customer meant the bilge pump cam on drained the battery and the bellows filled from the inside