No, it is a 97 tamagotchi not a 05... also the buttons worked fine a few months ago but now i have to use something pointy just to press the buttons for anything to happen.
I know what you are talking about as Mimitchi Tamagotchi is exactly like this. The buttons after all the use have become nearly impossible to press without using my nails. Your description sounds exactly like my problem. I have not tried to fix it, I'm so weary about opening Mimitchi Tamagotchi up, so I simply have not. But I have some ideas.
My guesses on the possible reasons for this problem...
1. Dust between the button and the contact on the board. Simple dusting maybe with an air can might work?
2. Maybe the circuit board over the years has loosened, pushing it back into the casing more, leaving the button unable to touch the contact without being pushed much further in then normal. Perhaps opening the tama and making sure the circuit board is secure in place could bring some discoveries?
3. The worse possible solution of course is that the contact has worn out and eventually will no longer take input from the buttons.
I'm just rambling here, I haven't tried anything yet, but maybe this will help a little? Either way I'm sorry to hear it, I sympathize with how your feeling.