Newbie's Gen2 no Ready light after Prolong install

Hello all. I am new to the forum but have owned my 2005 Prius for 18 months. Now has 110,000 approx. I just bought the Deluxe Prolong kit and have been installing the cable today. The car was working fine. I installed the cable and tested the charger per instructions and it worked. I put the car back together up to attaching the ground wire on the aux battery. When I attached that there was a good spark (rather unexpected). Once bolted down I thought I had better check if the car would start. It doesn't. Red triangle, check engine, brake (even though it is not set) lights all on. Ready light not on. I have the Torque app installed. It is reading the HV battery voltage around 15.8 on all modules. The app is reading the aux battery at 11.6 V but when I put the digital VM on the battery it shows about 12.3. Torque is not reading any fault codes.
Any suggestions would be much appreciated. Thanks

 

Thanks for your replies. I think you may have been right about the safety plug - pushing the lever down after it is inserted. It started and ran. It has been an interesting few days since that event. I looked under the battery cover and found that one of the modules (in block 4) appeared to have a very tiny electrolyte leak such that it had welded the orange plastic bus bar holder to the module. The voltage was in line with all the other modules but I decided to order a couple of used modules on Ebay anyway. I drove for another 300 miles or so with everything looking good after the one Prolong charging session (which took the battery to 241 V in about 20 hrs) and then pulling up my driveway after a long trip the red triangle came on (I got real lucky there - it could have happened while going over one of the big bridges over the Delaware R). The fault codes were PA 080 and P3013 and by looking at the block voltages on Torque that block 3 was about 15.9 while the others were well over 17. So, today I received my 2 modules. I replaced the clearly bad one (reading about 6.5 while the others were reading 7.9 V) and the leaky one. Now the whole battery is on the Prolong charger. I was surprised to find how easy it is to take the battery out, apart and replace modules. I realize I am not doing it perfectly by checking each individual module but this will have to do for the time being.