Help please, no start,no lcd did everything

[drcuadrado@gmail.com]

hi dear owners, i really need your help, I made a mistake trying to jumper a dead battery in my car(1990 lt5 zr1), change my battery for a new one and my symptoms are no lcd, no cluster signs in the left side, no start ( when i turn the key the radio turns off) I thought it was the ecm and buy a Used one here from forum friend, put the good one and its the same, check continuity from the 20amp cable from the battery to the Orange cable pin and its ok, I get 12.7 volt to the pin b11 and with ignition on from pin b10( with a multimeter touching the pin with the red Pencil and the black multimeter Pencil to the battery negative)
Please I dont know Where to look, Im in Argentina and in here we dont have corvette mechanics. Im really sad because it doesnt start and getting me very frustrated I thought it was the ecm but dont
Please any advice that could help me will be grateful
Im sorry about my english
Thanks in advance
i will attach a Pic from the cluster