Yarris cdx 00' buggered a few issues, please help

[daveg7]

I have a Yaris CDX .998l , 00' jap import that is buggered up, It was running fine then when to start it and it was turning but not starting, someone at work said the battery was low and got his jump leads out i connected them up on my end and after about a minute I lost all the dash and it wouldnt even turn, I quickly checked his conections and he had connected the jump leads around the wrong way around, I disconnected straight away, I checked the fuses inside and all were ok, but in the engine 3x15 amp fuses were blown and on the battery power cable one of the 100 amp fuses was blown i replaced the 3x15 amp fuses, but each time i turn the engine it the EFI 15 amp fuse blows I, then tried to reconnect the 100amp fuse by simply re-pressing the strip wire together and the dash came back but the EFI 15amp fuse now blows when a new one is placed even when no key is in the ignition, called AA and he said that his system can not speak to the ECU but it is displaying on dash for a spit second befoe fuse blows and i would probably need a new one? have sourced a used ECU import with identical model number and part number. so if I simply swap the ecu over will this stop the efi 15amp from blowing and will i need to reprogram my origanal keys to start it or is there another problem, please tell me its not a total loss? the centeral locking is also not working would this be due to the ecu being buggered, and if all is ok with that? what stoped the car from starting in the first place?

all help in greatly appreciated