If your tab is actually heating up, I suggest you take it to the shop or technician immediately! If it's just warm to the touch, try to reset it to factory settings. See http://galaxytablettalk.com/galaxy-tab-tutorials/how-to-reset-samsung-galaxy-tab-to-factory-settings for details. If that doesn't work, check that the charger is working (either by trying another device with the charger or, better, by trying your tab with another charger).If the problem is not with the charger either, your tab may be faulty. It could be a problem with the battery or with the electronics. Either way, you'll need to take it to a professional to be fixed.