Now you've bricked your PS4 and it asking to install software update. We are assuming that it is not using your internet to download update. To make your Play Station 4 working again you need to download the update file first. You need to have either USB pen drive 2.0 or 3.0 both works well or external hard disk. Fast internet connection is required as you are going to download a large file.
Follow the steps to reinstall PS4 software update.
Step 1. Download the software update from this link. Scroll down untill you find the download link like the below picture.
Step 2. Connect pen drive with your computer. The official page state to have USB 3.0 pen drive but this works with any standard 2.0 flash drive too. Format your pen drive either in FAT or exFAT format first.
Step 3. Once after format, create folder PS4 and inside it make UPDATE folder. Put the PS4UPDATE.PUP file inside update.
Step 4. Connect your pen drive with PS4. Start it and push PS button on your controller. You must have to connect your controller with USB cable.
Step 5. Confirm the update by pressing X key when it ask for "Connect a USB storage device that contains update file ...".
Step 6. Wait for around 10 minutes the complete process will be done automatically.
Step 7. Once everything is done fine, it will ask for you to start the initial steps.
Step 8. Set the time, date and login with your PSN ID and start playing games.
Q1. My PS4 is showing "CE-34788-0 Update file cannot be used."
A1. You need to make sure that you have downloaded the right update file. Follow the step 1 and download the file with size 800+ MB.
Q2. "The PS4 could not update the system software using a USB storage device Error Code CE-30774-1", help!
A2. Make sure you have formatted your pen drive or hard disk in FAT or exFAT format.