My iPad might have water damage + Apple Logo flashing every second

Water and electronics generally do not make happy bedfellows. Your iPad is not designed to be water resistant. While it will survive being splashed with water if immediately dried, it will almost certainly suffer irreparable damage if it is allowed to get wet, or is submerged for any length of time.

If the worst should happen, speed is essential. If the iPad gets wet, it should be immediately dried with an absorbent towel - then set aside in a warm, dry location to throughly dry - possibly for several days. The iPad should be turned-off - and no attempt made to turn-on, use, or charge the iPad until you are absolutely certain that the iPad has fully dried out. Pay particular attention to the charging port.

If your iPad does not recover, you would be best advised to need to visit to the Genius Bar at your local Apple Store or Apple Authorised Service Provider (AASP) where the iPad can be assessed for damage - and you can explore your available options:

Genius Bar Reservation and Apple Support Options - Apple

It's better to visit apple authorised service centre, sounds like ur phone may have sustained water damage. Do u happen to have protection plan like protect+ for it? It'll help you save a lot of cost.