The WS2811 LEDs don't light up

I'm sure I'm doing something wrong but I need some help to understand what.
I hooked the WS2811 LED string as in the video at http://www.espruino.com/WS2811. White to GND, red to BAT and green to B15.
I connected a battery to the white battery plug. This might be the problem because it's a power pack made by 4 1.2 rechargeable AAA batteries, so it's 4.8 V instead of 5 V. However the LEDs are powered because they briefly flash when I put the red wire into BAT (but they do that even if the battery if off.)
This is what I type into the Web IDE.

SPI2.setup({baud:3200000, mosi:B15});
=undefined
SPI2.send4bit([255,0,0], 0b0001, 0b0011);
=undefined

No LED lightens up. I tried to send the commands to the Espruino in the white part of the IDE, no success.
I tried a different baud rate of 6400000 because I read on the forum that not all the LED controllers might work with 3200000, but nothing change.

Is the 4.8 V battery the culprit? I don't have a 5 V one but I'm thinking about flashing a loop into the board and powering it with a 1 A/5 V Samsung charger into the micro USB port. Is that OK or it will be too much for the board?

Thanks.

So you're using the Espruino board? Does it have the latest firmware on it?

You shouldn't actually need batteries - if you're plugged in via USB then the board will provide up to an amp from the USB's power.

Last thing I guess is did you use the right end? The lights should be marked with DI and DO on the PCB inside the light itself - you need DI. Sometimes it's pretty hard to see which is which.

Yes, I updated the firmware yesterday before starting to experiment. I think I used the right end, the one with the female connector. The green cable ends up into a connection labelled DI on the PCB. That green cable has maybe a resistor patched in. The shape is the same as the ones in the reward but it's protected by black tape and I can't verify it unless I tear it apart. I'll check the wirings with a tester.
Thanks!

That sounds exactly right. I'm not sure what the issue is then - I actually tested again with the current firmware and it does work fine here...

at best buy a 5v power