What a mechanic actually checks first
On a house call for a no-charge complaint, the sequence is fixed, because each step rules out a cheaper failure before anyone talks about the expensive one. First the charger gets tested by itself: plugged into the wall with no bike attached, and its output measured at the plug with a multimeter. A healthy charger reads at or slightly above its labeled voltage. A dead reading ends the diagnosis right there.
Second, the charge port goes under a flashlight: bent pins, green corrosion, road grit packed into the barrel, and heat discoloration on the plastic, which is the sign of a worn connection arcing under charge current. The plug gets seated and gently moved to see whether contact is intermittent.
Third, the battery itself. We measure resting voltage at the discharge contacts. A pack that shows reasonable voltage but refuses to take a charge points back toward the port or the charge-circuit fuse. A pack that reads at or near zero after sitting drained is frequently a battery management system or connection issue rather than dead cells, and there are wake procedures a tech can attempt without ever opening the case.
Only after all of that does the conversation turn to the pack internals, because that is the one outcome with a serious price tag attached.
DIY or call a tech
The quick checks in the section above settle more of these calls than owners expect, so run them first and read the results this way: if the charger LED never lights on wall power alone, the charger is the fault, and a replacement matched to your pack's voltage and plug is the entire repair. If the LED lights but the port looks dirty, clear loose debris with a dry toothpick or compressed air with everything unplugged, then try again. And confirm you are charging with the charger that shipped with the bike: a borrowed charger with the wrong voltage will refuse to work at best.
The line is the multimeter. Once diagnosis requires measuring voltage at the battery contacts, attempting a BMS recovery, or opening anything, it is tech work. The energy stored in an ebike pack does not forgive guesswork, and our recommendation is absolute: never open a lithium battery pack, no matter how confident the video tutorial sounds.
One more safety note on charging, offered as our recommendation: charge on a hard, non-flammable surface where you can see the pack, and unplug once the light goes green. If a pack has been dropped, dented, or soaked, keep it off the charger entirely until it has been inspected.
What the repair costs and why
Our network's typical range for this symptom runs $60 to $800, and the spread is the diagnosis. The $60 end covers the good-news outcomes: a charger swap, a port cleaning, or a lockout recovery on a pack whose cells are still healthy. The $800 end is a failed cell group, which means pack replacement, priced mostly by brand and availability. That is why the brand table below is worth a look before you panic or shop: orphaned and legacy packs sit at the top of the market, and the older 52V Juiced batteries are the clearest example, where thin supply can push the job as high as $900 and the honest fix is a quality rebuilt or third-party pack.