Made by SLoanLED
This is a grey 6cm by 3cm box that says SloanLED in its moulding, on the label it says P/N701564-4-F, and its a 12v system.
SloanLED quad LED is a daisy chain system that manages 4 RGB LED's which are all attached to the box.
It consists of 4 RGB LED's on cables that connect to a grey box which manages the power via 2 x 4 pin connectors (1 x Male & 1 x Female) designed to daisy chain from a control box like the SloanLED Control 40 (sold separately).
Please see images for spec on grey box.
How to test
Symptom - No LED's lighting on your hot tub.
With a multimeter test to see if the system is getting power, and if so test with multimeter on the pins inside the male connectors, you should get 12v on 1 of the pins on both of the male connectors. And if not you will need a new control unit.
If you have a 12v coming from the connectors then you may have a faulty LED or complete faulty chain of LED's, testing is much the same as old Christmas tree lights from there on.