Overall job, from removing your old garage door until you are pressing the remote for your new door, normally runs about three hours.
Overall job, from start to finish, normally takes one and a half hours, assuming all of the support brackets and wiring can be re-used.
Your garage door spring has broken! This is not a DIY job. Call your garage door specialist, preferably Deyo Doors.
Your gear is worn inside the opener. Call your garage door specialist to replace it.
It is best to check on either side of your garage door for a safety device sensor. If this is blocked or misaligned, then your garage door will malfunction. The flashing lights (or clicking) is an indicator. If you cannot realign or unblock the sensor, then call your garage door specialist, preferably Deyo Doors.
If you do not have installed a key disconnect on the front of the door, then you are at the mercy of your electric company. Otherwise, have your garage door specialist install a key release/disconnect as soon as possible, so you are never left stranded.