Make cell flash a specified number of times upon event

I am building a template in which people are to paste data into one sheet, and then navigate to a different sheet.

I want to call the user's attention to a specific cell (M2) on a sheet called "Pivot" as soon as they click on the sheet tab.

How can I make it so that M2 in Pivot flashes three times as soon as the user activates the sheet?

Alternatively, I might prefer that M3 has a flashing border around it, but I'm sure I'll be able to figure that out if I can get help with the flashing cell M2.

I found this code, and tried to adapt it to my needs, but was not successful:

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Thanks for all help.

Hi
pleaser use code tags instead of HTML tags ( they do not allow scrolling). I have changed them for you

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But if deactivate sheet then the ontime must be canceled and cell color return back.