@Kapiushon: Please can you try pressing the Volume Up and Power buttons together to see if you're able to power the A50 on in this manner? If not then please visit a Samsung Support Centre, where an engineer will be able to inspect the device for you. To find your nearest one please check the link below, select 'Mobile Device' and enter your post code.
http://www.samsung.com/uk/support/servicelocation/ Please be advised that if the engineer deems the issue to be the result of liquid damage then a charge will be applicable to cover the cost of the service. For your peace of mind, any costs will be communicated to you prior to the service going ahead.