Hi everyone. I'm trying to help a friend. He has been storing doge for a long time, and now he found a pair of address and private key. Doge at this address. But the friend does not remember in which wallet he created the address. He tried to import the key into CoinexWallet, but got the answer that the key is invalid. This private key starts with 6. This is strange, I thought that Doge keys always start with Q. Please tell me, what format can a key have that starts with 6? In which wallet should I import it?