Carpet + Boost lights flash simultaneously

This unit appears to be the North American counterpart to the UK model "IF200UK 31" Shark DuoClean Cordless for anyone trying to work it out.

Disassembling the hand held unit to get to the motor and two PCBs is definitely difficult but doable.

I'm wondering if the carpet and high suction (ION boost in US) lights blinking indicates a specific fault?

I press the power button and the unit attempts to power up as it spins the motor, but it is as though there isn't enough power or a fault condition is encountered straight away and the power is withdrawn in less than 1 second followed by the blinking lights.

The lights blink away until it turns off to standby. I can press the power button and repeat this indefinitely (at least until the battery drains if I were to waste a day trying).

It is as described in this question - Boost & Carpet lights flashing..

Anyone experienced this?