TROUBLE (SHOOTING)--help!

[FOR THE MORE TECHNICALLY INCLINED & TO THE POINT: PLEASE HELP ME TROUBLESHOOT WHY MY MERIDA GOES FROM "FULL" ON THE BATTERY GAUGE, TO BEEPING REPEATEDLY AND FLASHING AS THOUGH THE BATTERY WAS COMPLETELY DISCHARGED AS SOON AS I PLACE A DEMAND ON THE PEDALS THAT WOULD NORMALLY ENGAGE THE SYSTEM? THE BATTERIES WERE INDEED TESTED AS AN OVER-FULL 12.9 VOLTS EACH FOR BOTH OF THE LISTED "12V, 10AMP" BATTERIES..IS IT THAT THE AMPS ARE TOO HIGH PERHAPS? COULD THE CONTROLLER OR MOTOR BE DAMAGED?? HOW DO I TROUBLESHOOT WHAT THE PROBLEM IS??? IF THIS INFO IS ANY HELP AS WELL: WHEN I SET THE CHARGER ON, IT GOES TO THE GREEN COLOR ON IT INDICATING A FULL CHARGE WITHIN SECONDS. PLEASE HELP, AS I LOVE WHAT THE MERIDA DOES, & HAVE ALL THESE COOL PLANS TO GET IT GOING FASTER AND FULLY AUTOMOTICALLY WITHOUT PEDALING!! THANK YOU. AND NOW, THE ARTSY VERSION OF THE STORY FOLLOWS FOR THOSE SO INCLINED...]

Hello--first off, this is an absolutely terrific site. I have gained much pleasure, unlearned as I am in electronics and electrical bikes specifically, from my readings of the posts of others herein. Absolute pleasure~

What is no pleasure is my Merida 500 (looks like it dates back to 2000 from a sticker I found behind the battery on the seat post).

With gas in excess of $3.50, I finally hit the tipping point for motivation to find replacement batteries after not having rid the bike for the past year. Of course the old 12V, 9ah(I think that's right) batteries that fit neatly into the awesome detachable battery case are nowhere to be found, as I've read others write.

So I purchased some larger ones and am making do. However, after an ordeal of cosmic proportions (for this impatient newbie anyhow)--which included arching of wires and screaming as my flesh slightly burned, and the intense frustration of not knowing quite how to arrange the wires for hours...I finally got the "BEEP" & then the red light which started at 1/2 full on the battery gauge climbed up to 3/4 full, and then finally landed on 100% full and stayed there, red and shiny.

I was thrilled. It was 1am, but I was determined to drive to work THEN AND THERE (5miles), with plan to sleep there until opening time!! But first I needed air, and I set out for the gas station across the street. After the tires felt solid, I got back up on the bike & was very excited to feel that wonderful "unseen hand" push I had known before riding this bike. But it was not to be! The bike beeped at me again and again and there was absolutely no torque for even the briefest instance that I could sense in the pedals; the bike battery indicator went from full to a flashing red empty as I remember it having done in the past when the battery was virtually fully discharged. I think this can't possibly be the case because I saw it tested in the battery store (reputable and overpriced Batteries Plus), and it was a solid "full" just before and after turning the key off-on again.

Please help me to trouble shoot this problem. How would I go about locating where the trouble stems? Could I have wired it wrong and it only makes the battery indicator show up positively, but not allow for the juice to flow through the motor? Could I have fried the motor or controller (whatever the heck that thing is), or something else within?? How can I determine this???

Any help with troubleshooting this and getting my Merida street-ready and running is greatly appreciated! Thanks.