I
verb
1
BAD : I got out of bed and opened the radio to listen to the news.
GOOD : I got out of bed and turned/switched on the radio to listen to the news.
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turn on/off (or switch on/off ) a light/radio/television (NOT open/close ): 'The children are not allowed to turn on the television without permission.'
2
BAD : If anyone tried to open a new topic, she would immediately interrupt.
GOOD : If anyone tried to introduce a new topic, she would immediately interrupt.
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introduce a (new) topic/subject/argument (NOT open ): 'You can't introduce new material in the last section of a report.'
II
adjective
BAD : I couldn't buy a newspaper because the shop wasn't opened.
GOOD : I couldn't buy a newspaper because the shop wasn't open.
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Use opened to describe an action and open to describe a state. Compare: 'The shop was opened at 8 a.m. and stayed open until 6 p.m.'