Troubleshooter: What to Do When Your Underwater Scooter Won’t Start

So your underwater scooter won’t start, and you're staring at it like it's betrayed you.

Whether you’re gearing up for a dive or just got back from one, there’s nothing more frustrating than a dead scooter.

Before you throw it in the back of the garage or worse into the sea—let’s break down what’s likely wrong and how to fix it.

First: what “normal” looks like on the MANTA

• Start sequence: put the scooter in water, unlock the switch, then hold both triggers to spin the prop. Release the triggers to stop. Speed up by holding Left and tapping Right twice; slow down by holding Right and tapping Left twice.

• Locks & latches: there’s a switch locker and a battery pack locker. If either isn’t set right, it won’t run.

• LEDs: a fast single flash means <20%—charge it.

• It floats: lose your grip and it will shut off and float. A protection leash ships in the box—use it.

• Core specs (for sanity checks): 5.0Ah 25.2V (126Wh) battery; charger DC 29.4V/2A; 35-min max runtime; 131 ft/40 m depth; 7.7 lb weight.

60 second triage

1. Unlock the switch. If it’s locked, nothing happens.

2. Seat the battery until the locker clicks; reseat if sandy or gritty.

3. Start it in water and squeeze both triggers together.

4. Check LEDs. Quick flashing = charge it first.

5. Spin the prop by hand (power off). If it’s stiff, clear debris. The prop covers are detachable for cleaning.

If it’s still dead, go deeper.

Deep diagnostics

1) Power & charging

• Charge fully on the OEM charger (29.4V/2A). Normal time: 2–3 hours.

• Do not charge hot or wet. Let the pack cool if it’s warm after use; do not plug in if the port/cord/outlet is wet. The pack must not be charged above 48 °C/118 °F.

• Contacts clean & dry. Keep the battery connector dry at all times; wipe the unit with a damp cloth only (no detergents).

Why this matters: a tripped battery protection circuit or poor contact will mimic a “dead” scooter. Charge properly, dry thoroughly, and reseat.

2) Controls & lockouts

• Switch locker: verify it’s unlocked before pressing the triggers.

• Both triggers required: if you press only one, it won’t run. Always start in water.

• Speed not changing? Use the hold-Left + double-tap Right (faster) / hold-Right + double-tap Left (slower) combos.

3) Prop/impeller obstruction

• Power off, unlock off, remove leash.

• Pop the detachable covers, remove hair, fishing line, or weed; the prop should turn freely by hand afterward.

4) “Won’t run after power-on” 

• The manual notes sand/salt crystals can stall the motor. Submerge for a few minutes and start repeatedly until normal, then rinse thoroughly.

5) Water, rinsing, and what “wet” really means

• The outer body floods during use; connectors are waterproof, but you should soak/rinse in fresh water right after each session and dry before storage. Don’t use detergents.

• Keep connectors dry when charging or storing; salt + moisture = corrosion over time.

6) LED patterns & protective shutdowns

• Low battery: fast single flash (<20%). Charge.

• All four LEDs flashing: self-healing function engaged. Release the switch and wait for the indicators to go out; restart normally.

7) Cross-testing (to isolate parts)

• If possible, try a known-good charger or spare battery (same 126 Wh pack) to separate charger vs. pack vs. scooter issues. Specs are on the tech sheet for matching.

Symptom → cause → fix

Maintenance that prevents no-starts

• After every session: soak/rinse in fresh water for a few minutes; dry before storage.

• Never use detergents; wipe with a damp cloth only.

• Keep out of direct sun/heat when not in use (heat kills batteries). Operating environment is −10 ° to 40 °C.

• Charge/storage sanity: for longer shelf life, store Li-ion around 40–60% charge in a cool place; avoid storing fully full or near empty. (General Li-ion best practice.) 

Battery & travel

• Installed batteries (like your MANTA) are typically fine in carry-on; spares 101–160 Wh (your 126 Wh pack qualifies) are carry-on only and limited to two with airline approval. Always check your carrier. 

• Make sure the Wh rating is labeled on the pack (required) and protect the terminals when carrying spares. 

Recommended: Flying with Your Underwater Scooter: A Comprehensive Guide to Air Travel Rules

Field checklist

• Switch unlocked

• Battery latched (audible/firm click)

• In water, then both triggers to start

• Prop & guards clear; covers refitted

• LEDs not in low-battery flash

• Connectors dry before charging

• Post-use soak/rinse, then dry before storage

(All behaviors above verified from the MANTA manual.)

When to stop and seek service

• Persistent all-LED fault even after releasing the switch and waiting,

• Visible corrosion, cracked housings, damaged latches,

• Battery swelling, hissing, or chemical odor,

• Repeated failures after correct charging and cleaning.

Grab your model/serial, charger model, clear photos of contacts/latches, and list the steps you’ve tried; then contact support. (Manual contact: customer@asiwo.com.)

Bottom line

On the MANTA, most no-start headaches come down to switch locked, battery not fully seated/charged, not starting in water with both triggers, or a jammed prop. Work the list above—fast—and you’ll either be back in the water or have clean evidence for a warranty fix.

FAQ

What’s the correct start sequence?

Unlock the switch, submerge the scooter, then hold both triggers to run. Release either trigger to stop.

It won’t power on—what should I check first?

Make sure the battery is fully charged and latched with a clear click, the switch locker is unlocked, and you’re starting it in water.

Can I test the prop out of water?

No. The MANTA is designed to start only in water; dry-running can prevent start and risk damage.

It stops mid-ride—why?

Auto-shutoff when you release the grips, a low battery, or a jammed prop (hair/line/weed). Regrip, clear debris, and restart.

What’s the best post-use care to avoid no-starts?

Rinse/soak in fresh water, dry completely, keep connectors dry (no detergents), and store cool. Charge with the OEM charger only.