I just downloaded the 2.5.4 version and it is the same story as the latest version... I type my words but I can't click next...
Are you 100% sure you are typing the seed correctly? There is a checksum to detect typos. A single typo in the seed will prevent the "next" button from lighting up.
BTW, older versions of Electrum did not have the checksum, so if you type the seed wrong it will seem to work, but the addresses will be all wrong and you won't see your history/balances. That is why they added the checksum in newer versions.
I could try a brute force attack on the seed to look for a typo if Pappiony wants. Would require the seed, an address that belongs to the seed and an address where I should send the coins to if it was a success.