After jump starting 2001 blazer all dash board lights/gauges flashing ,i used the jump start charger to restart the blazer , soon i noticed that speedometer was not working ,took the blazer fr battery change ,tech removed the red terminal while car was running to chk if alternator is ok ,and i noticed that all dash borad gauges started flashing ? replaced with new battery ,it stopped fr a while then started flashing again ?none of the gauges are working ?can anyone pls advise ,what went wrong ?and how to fix it?