Apple Watch while connecting Watch unpairing

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I purchased cracked US GPS version Watch & replaced the display

After replacement display Watch was very slow booting up

I did erase all contents on my watch & then I unpair with my iPhone

then while pairing became more time to boot up & while connecting Watch it was unpairing automatically with out any pop up message like pairing failed

I’m from India , here no Apple Pay

but Watch from USA

Help me to fix this issue how resolved

unfortunately i don’t have old screen also