I've got a X7 that I've not used for a very long time (several months). The last time I was using it everything was just fine but today when I de-shelved it and connected it to power nothing won't happen. Usually there is a blue led indicating it's powering on - stays black. I've also tried with an universal power adapter (making sure to use proper voltage settings) to check if the adapter is maybe faulty - same story. Any ideas why this could happen?