Comment 13 for bug 1863434

Same here.
1st try: After install i had to use power button to restart because system reboot froze in tty. First boot went normal but grub never showed up. At the second boot grub still didn't appear and the system froze on a blank screen. I wasn't able to change to tty and had to reboot using power button.
2nd try: Downloaded ubuntu 20.04 again and created a usb disk using Rufus. Installed the system, had to use power button to restart because system still froze on reboot. First boot went normal but grub never showed up. This time i edited /etc/default/grub changing option hidden to menu and timeout to 10. Updated grub and rebooted. Grub still didn't appear and the system froze on blank screen again.

Dell Vostro 5470
Nvidia Geforce GT 7400m - driver 440 installed automatically on system installation
Dual boot windows 10