trust me...
read any battyer charger.. says it should be disco'd from the vehicle especially with CPUS
i test this shit for a living-
auto manufactures cant rely on what shitty jap chargers say on the side / unfortunatly we have to idiot proof things.
GM requires a 26volt jump start test- SMOV (static minimum operating voltage) for most components is 5.5-6.2Vdc
i cant imagine DXler requires component failure anything less
Being that the system is so "smart" i doubt there are any CPU issues.
i would guess smoked alternator and dead cell in the battery, but i would have to observe 1 or 2 things