Multicouloured Vertical and horizontal lines across my TV screen

I have a hanspree tv, after putting it up on the wall we turned it on and noticed both multicolored horizontal lines going across the top of the TV and multicolored vertical lines mainly from the middle to the left hand side. This is leaving us unable to read what's on the telly. We think it could either be a result of having the telly face down or not putting the screws in correctly?