Help with a poorly 41hz Amp6

I put a portable speaker box together with a lot of help about 5yrs ago, it only has occasional use maybe 5 to 7 times a year and the only regular problems I've had are loose speaker cables. But after charging it last night I can't get any sound and I don't know why, I've checked for loose cables and the power light turns on but I'm not hearing the usual small pop from the speakers as I turn the on switch.
Any suggestions would be appreciated however you might need to use small words as all the electronic circuitry stuff was performed by an old acquaintance, so I might not understand ;)
1 to 3) I've checked those speaker cables. Nothing is loose or detached. Nothing is missing.
As to the overwhelming lack of information I know it's an amp6 amplifier kit. I know it's running a pair of 6.5in 4ohm speakers and a pair of tweeters through a crossover. And I know it's running off of a 12v 7ah sla battery. That's pretty much all I know.
If you can think of any info I haven't thought of though please share...
Ok thanks, I didn't know you could do a battery test like that, I'll give it a try. I don't have any other speakers but I'll try to borrow some.

Alternatively I'm thinking I might start over and try for a similar but lighter setup so can you please recommended a small amp that'll help a couple of coaxial marine speakers chuck sound outside. I'm not wanting ridiculously high quality sound i just need something that'll cope with loud thumpy dance music...