Same Problem here too.
Fresh Install with OS Image “pi-topOS-sirius_C781_2020-12-22_04-11-42.zip”. Clean Install and Reboot afterwards…
OLED Display remains Black.
Some Debugging Informations:
pi@pi-top:~ $ ps -ef | grep python | grep pt-sys-oled
root       876     1  3 20:29 ?        00:00:18 /usr/bin/python3 /usr/lib/pt-sys-oled/pt-sys-oled
pi@pi-top:~ $ pi-top  devices
HUB ==================================================================================================================
pi-top [4] (v5.4)
PERIPHERALS ==========================================================================================================
[   ] pi-top Touchscreen 
[   ] pi-top Keyboard 
[   ] pi-topPULSE 
[   ] pi-topSPEAKER (v1) - Left channel 
[   ] pi-topSPEAKER (v1) - Right channel 
[   ] pi-topSPEAKER (v1) - Mono 
[   ] pi-topSPEAKER (v2) 
pi@pi-top:~ $ pi-top oled draw "hallo"
Press Ctrl + C to exit.
# Nothing Changes on OLED Display!! OLED Display still remains Black.
pi@pi-top:~ $ cat /etc/os-release 
PRETTY_NAME="Raspbian GNU/Linux 10 (buster)"
NAME="Raspbian GNU/Linux"
VERSION_ID="10"
VERSION="10 (buster)"
VERSION_CODENAME=buster
ID=raspbian
ID_LIKE=debian
HOME_URL="http://www.raspbian.org/"
SUPPORT_URL="http://www.raspbian.org/RaspbianForums"
BUG_REPORT_URL="http://www.raspbian.org/RaspbianBugs"
pi@pi-top:~ $ sudo apt update
OK:1 https://apt.pi-top.com/pi-top-os sirius InRelease                             
OK:2 http://archive.raspberrypi.org/debian buster InRelease                                                 
OK:3 http://raspbian.raspberrypi.org/raspbian buster InRelease                                              
OK:4 http://packages.microsoft.com/repos/vscode stable InRelease                    
Paketlisten werden gelesen... Fertig      
Abhängigkeitsbaum wird aufgebaut.       
Statusinformationen werden eingelesen.... Fertig
Alle Pakete sind aktuell.
pi@pi-top:~ $ sudo apt upgrade
Paketlisten werden gelesen... Fertig
Abhängigkeitsbaum wird aufgebaut.       
Statusinformationen werden eingelesen.... Fertig
Paketaktualisierung (Upgrade) wird berechnet... Fertig
0 aktualisiert, 0 neu installiert, 0 zu entfernen und 0 nicht aktualisiert.
pi@pi-top:~ $ vcgencmd bootloader_version
Sep 10 2019 10:41:50
version f626c772b15ba1b7e0532a8d50a761b3ccbdf3bb (release)
timestamp 1568112110
update-time 0
capabilities 0x00000000
pi@pi-top:~ $ date -R
Sun, 03 Jan 2021 20:47:43 +0100