how can i fix my 39" lcd television myself?

i have a 39" lcd television made by umc and is model number 39/63G-GB-3BFTCU-UK , the televisions product code is UW39C63BFTCUG527 , the television worked fine until recently when it switched itself off and now it turns on but stays on sometimes for a few minutes other times longer or sometimes as soon as i turn it on switches itself off does anyone know what the problem may be and/or maybe how i can possibly fix it myself