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Razor MX350
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So guys I need some guidance. I got my little man, Keaghan’s, MX350 all set to start teaching him to ride it over this past weekend. Dude has been driving a Bravos 24V Grave Digger since he was 11months old & is a total gearhead so next step up from his PW KFX & DuneRacer was the MX350 since it can grow to his abilities. I installed the top speed limiter & Variable Throttle w/ controller from ESP with no issues & added some Hardline training wheels just until his balance bike skills transfer over & he gets the whole twist throttle & handbrake idea. ANYWAYS after we finished up Saturday, I plugged up the 350 to charge after turning it off. Next morning I go into the garage to get the bike to find the charging port cover ripped off, charging cable unplugged, bike power switch turned on, & one of my Phillips screwdrivers laying there at the scene of the crime. After asking my son what happened, my almost 3yr old Keaghan tells me that he wanted to “ride his brawp cycle but he had to fix it by screwing in the batteries” (via the charging port after already turning the power switch ON). He then said it “bit him in his hand & he left it alone”. I’m assuming he shorted something out via the charging port & haven’t checked the fuse yet but now it won’t even power on when I turn it on whether I charge it or not. I’m hoping y’all can point me in the direction of items to test to see if he fried the bike. I’m thinking this order:
1. Fuse
2. Batteries
3. Motor
4. Controller
Any ideas would be totally appreciated yall and thanks ahead of time.
 

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Sounds like you will more than likely be upgrading the speed control.

Here is a nice how to video and the speed control that I recommend
 

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Sounds like you will more than likely be upgrading the speed control.

Here is a nice how to video and the speed control that I recommend
I've been "bitten" a couple times working on these Razors. Usually touched a positive and negative battery post at the same time. Each time the 30amp inline fuse blew before any other damage occurred. I'd bet it's just the fuse.
 

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I've been "bitten" a couple times working on these Razors. Usually touched a positive and negative battery post at the same time. Each time the 30amp inline fuse blew before any other damage occurred. I'd bet it's just the fuse.
100% definitely check the fuse

There is a transistor that's embedded in the epoxy this transistor is responsible for telling the speed control circuit if the charger is still plugged in or not if the charging port pins get shorted while the power of the speed control is on then it burns out that transistor and the speed control will think that it's plugged into the charger even though it's not and will not turn on.

if you open up the speed control and you're lucky and the epoxy coating is really thin not existent or it missed the spot where it covers the transistor then you can save it by replacing it with a common npn 2N3904 40volt transistor all of the razor stand up scooters and small sit-down motorcycles that have the two-step and three-step relay driven speed controls as far as I know use the same circuit

Follow the traces from the charging wires the other transistors are for the brake safety and to fire the relays from the throttle input.
 
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