COMENo Open button after a COME APK download
A browser can save a file without keeping an Open button visible. Check Downloads before assuming the transfer failed.
Find the completed record
Open the browser's download list and inspect the intended item. If it is still pending or failed, resolve that state. If completed, use the available file action or a trusted file manager to locate the same item.
Avoid another transfer by default
The disappearing notification or button may be a display change rather than a file problem. Starting another download can create duplicates. Match the existing file by source and time before deciding to retry.
Read Android's prompt
Opening the file begins a separate installer step. If the phone cannot handle it or warns about it, record the exact message. Do not add an unknown file-opening app merely because a browser action is not visible.
A useful next step
Use the completed-file entry as the starting point for Android installation.
Related: Resume after cancelling a COME APK installer