did open has "ed"

If you use open as past tense or present perfect tense or past perfect tense, it has "ed". But if you use it as present tense, no "ed".

e.g. Ben opens the bottle. I open the bottle. (present tense)
e.g. Jane opened the door for me yesterday. (past tense)
e.g. Bobby has just opened a can of coke. (present perfect tense).
e.g. Jenny had opened a shop in Shamsuipo. (past perfect tense)

Your dad is right!!
'Open' just like'Close'
Closed>>Opened
E.g. I opened the window after I got up.

Hope I can help you!!**

Your dad is correct, past tense, open has ed = opened.