the dell mini has failed to backup power and cant stay on too with AC plugged in... i ve changed the battery but the problem is continuing to exist....please i need ur assistance to fix this
It looks like the power supply is not doing it's job.
"...has failed to backup power..."
This is realy NOT clear. In fact, it hardly make any sence at all.
Did it fall?
It's hard to see the meaning of "backup" in this cntext. Backup apply to saving a safety copy of your data to some external storage or online storage, never to power or booting the computer.
Check the power supply connection to the wall and to the computer.