Lithium Ion batteries do not like being fully-discharged, so these are likely garbage. Disappointing. I bought this deal because it is a well-rated unit on the regular Amazon site and seemed to be a decent value. I was very disappointed when both boosters arrived with the power switch in the “On” position and no power level displaying. I put them both on chargers to see if they come back, but they are still blinking 0% level over 10 minutes later. I will keep an eye on them and check temperature. If they don’t start showing any charge or start climbing too hot, I will be sending them back.
Before you give up on them, you might give them a full overnight charge. We see lots of batteries shipped drained for safety reasons.
Update: After I put the device on the charger and made the post above, I thought to measure the battery output voltage at the jumpstart terminals, and it was just under 13 Volts. After 45 minutes, the battery has increased to 5% and the output voltage has increased up to 14.15 Volts and charging temperatures have stabilized. It appears these units do have a low-voltage cut-off for the flashlight and USB output (but not on the jumpstart cable output port), so when used as a battery bank, the load won’t drive the voltage too low. Looks like they weren’t really “completely dead” at 0% and might be just fine. Nice.