Correct spelling, explanation: unlike many other words open doesn’t double the last consonant when adding a suffix, despite the rule of consonant-vowel-consonant ending. This rule usually applies, but on the condition that we stress the last syllable. In the case of opened we stress the o, so the last consonant doesn’t double. Therefore opened is the correct spelling, not openned.

Definition of opened:
verb, past simple tense of open, to have unlocked, unsealed, or made accessible something that was previously closed or shut; describing something that has been revealed or unfolded, often implying transparency or honesty.
She opened the door and welcomed the guests into her home.
The store opened its doors early for the Black Friday sale.
During the therapy, he opened up about his trauma.

Incorrect spelling, explanation: this spelling is wrong because in open we do not double the n when adding a suffix. The rule says that to double the last consonant there should be a consonant-vowel-consonant ending and the accent should be placed on the last syllable. Opened has the first syllable stressed so we do not double the last consonant. Therefore opened is the correct form and openned is wrong.

Incorrect spelling

Incorrect spelling

Incorrect spelling

Incorrect spelling