Let an overheated pack recover
If the clamps are connected correctly but the Error LED flashes red, NOCO identifies an excessively hot internal battery. Allow the unit to cool in a cooler environment before retrying. Do not interpret this warning as a request to crank repeatedly.
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No Boost light is another condition
With correct connections, a battery below two volts may not be detected. NOCO first suggests removing loads and retrying. If still undetected, stop and assess the battery rather than treating the missing light as proof of a bad booster. Record the light pattern and connection checks for support.
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Sources / references 1
- NOCO — GB40 support and troubleshooting ↗Reviewed Oct 8, 2026
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