My 2014 WR450 has always been a bitch to start. So much so that I'd just stopped using the magic button and kicking it. Fired right up, no problem.
Fed up, I took it to my local bike shop (who is AWESOME). They checked the usual things, like compression, leak down test, TPS, auto decompression, battery voltage, and finally the starter. Turns out that with all the work they did (for FREE), they gave me a new lithium battery and a new starter.
The starter was dragging and drawing way too much voltage, causing the voltage to drop too far which wouldn't allow the fuel injection system to work properly. That's why it always fired up when kicking because there was plenty of voltage for the fuel injection system, but not when using the magic button.
Anyway, the problem is solved. At 100 hours on the bike, it now starts just like it's supposed to--instantly upon hitting the e-start button.
Talk about service after sale. They had the bike for a week, several hundred dollars in parts, and they did it for free. If you want to know what shop it was, PM me. After talking to the manager, there are a couple of other bikes they are looking at for the same problem.