I’m sorry for your troubles. It can be a real pain in the bum getting the various DSI displays to work on different Raspberry Pi models.
I can’t find specific information regarding the connector on the Freenove display and you haven’t provided it. It sounds like you are expecting a 22pin connector but you don’t describe what is the connector on the Freenove display - if it is 15 pin, then I would think a straight 15 pin ribbon cable should work.
Personally, I’m using BTT TFT5 displays on my printers and they have 15 pin connectors that work fine with Manta M8Ps, a Manta M5P as well as my own custom board (which all have 15 pin connectors). I have them running on CM4s, a CM5, CB2 and Orange Pi CM4. So, it can be done.
The standard for Raspberry Pi boards is the 15 pin connector used on the Manta boards. The CM4 IO board had a 22 pin connector put on that has exactly the same pin connections as the 15 pin connector. My understanding is that the rPi 5 went with the 22 pin connector that is used on the CM4 board because it is physically smaller.
Just to show you:
The Raspberry Pi 15 pin DSI connector pinout
The CM4 IO Board 22 pin DSI connector pinout:
There is no difference in the pins used between the connectors and the signals are all identical between Raspberry Pi models. There is no difference in the DSI port signals between the Raspberry Pi 5, the CM5 and other Raspberry Pi models.
If you have the LCD flashing on and off, that sounds like it is getting power. On other DSI displays that I’ve worked with there is a power indicator LED that stays on while power is applied to the display. Does this one have one? If it does, then there’s a good chance that if it stays lit, then you’re good to go.
Looking at the Freenove page (which doesn’t have documentation), there seems to be a separate 5V power connection to the Raspberry Pi’s 40 pin connector pins 4 & 6. Do you have this on your setup?
Where did you get the dt-blob.bin code? I have had problems with that in the past as there are at least two versions available from Raspberry Pi and one of them didn’t work for me. You might want to look around there.
Looking at the product page I see:
Did you contact Freenove with questions?
Next, you should go through:
I don’t see any information on the Freenove displays but you might find something of value there.
The next stop would be reaching out to the various Raspberry Pi forums to see if anybody can give specific instructions as to what to do.
The good news is that this really a Raspberry Pi issue. That means you should be able to get more and better information as well as support from people who’ve worked with both the CM5 and Freenove display.
If you can’t find any help in the resources listed above, then post with more information regarding your hardware (including connectors and number of pins) as well as your set up procedure and what you’ve done to support the display.