curl --request POST \
  --url https://api2.rhombussystems.com/api/event/searchMotionGridWithActivities \
  --header 'Content-Type: application/json' \
  --header 'x-auth-apikey: <api-key>' \
  --header 'x-auth-scheme: <x-auth-scheme>' \
  --data '
{
  "deviceUuid": "AAAAAAAAAAAAAAAAAAAAAA.v0",
  "endTimeUtcSecs": 1641081600,
  "searchCells": [
    {
      "col": 5,
      "row": 3
    }
  ],
  "startTimeUtcSecs": 1640995200
}
'

{
  "error": true,
  "errorMsg": "<string>",
  "timeUtcSecsToActivityMap": {},
  "warningMsg": "<string>"
}