Technology is disclosed herein for quickly determining which erase block is bad if there is a failure in parallel erasing a set of erase blocks. The erase blocks may be tested individually in response to a fail of the parallel multi-block erase. A voltage generator ramps up the erase voltage from a steady state magnitude towards a target magnitude. The magnitude of the erase voltage is measured at a pre-determined time. If there is a defect then the erase voltage may fail to be above a threshold voltage after the ramp-up period. If the erase voltage is below the threshold voltage after the ramp-up period then the erase block may be marked as defective. If the erase voltage is above the threshold voltage after the ramp-up period then the erase block may be marked as good.