What should I do if the boost LED does not light up when my battery cables are connected properly?
If the battery cable connections are correct but the Boost LED does not come on, it indicates that the connected battery might be below a voltage of 2 volts. You need to either remove all power loads from your vehicle and try again or use the Manual Override mode if the battery is too low to be detected (Page 7).
From the official Noco Gb40 Boost Jumper Lithium Jump Starter manual, page 7
Have a follow-up question?
Answers from the official manual.
Common questions