Problem solved. The api was down. I contacted M5stack via Twitter. They resolved the issue.

I'm using three timer cams with a tiny solar panel, lipo battery and a TP4056 as a charge regulator.
I've soldered a diode between the solar panel and TP4056 to avoid battery drain in the dark. The camera's are in a remote location, and are functioning more than a month without a problem. The battery voltage is around 4.15 volt, so still almost completely full.

It's built like this image. My solar panel is a 5 volt 60mA panel. The battery is a 500mA lipo battery. The output on the right (in the image the dc-dc step up, my timercam is connected) in the image connects to the onboard connector of the Timercam. I've used the original plastic shipping case to construct a waterproof case for the components.

Problem solved. The api was down. I contacted M5stack via Twitter. They resolved the issue.

Thanks for your reply. The information is here:
link to docs (scroll down to http api)
My camera's have worked for several months, but the service is down for more than 24 hours.

I'm having trouble reaching the api website for my Timercam X. The URL isn't reachable for the last 24 hours.
The url is http://api.m5stack.com:5003/
Anyone else having this issue?

It's built like this image. My solar panel is a 5 volt 60mA panel. The battery is a 500mA lipo battery. The output on the right (in the image the dc-dc step up, my timercam is connected) in the image connects to the onboard connector of the Timercam. I've used the original plastic shipping case to construct a waterproof case for the components.

I'm using three timer cams with a tiny solar panel, lipo battery and a TP4056 as a charge regulator.
I've soldered a diode between the solar panel and TP4056 to avoid battery drain in the dark. The camera's are in a remote location, and are functioning more than a month without a problem. The battery voltage is around 4.15 volt, so still almost completely full.

Thanks for the support! I've managed to 'fix' it. Reinstalled the IDF with predownloaded V4.0.3 version.
I couldn't get the uint conversion working in the main.c. It came up with a lot of errors. So I decided to go for the quick and dirty solution; hardcoded sleep timer of four hours in microseconds. Not the way it supposed to be, but it works for me ;-)

Thanks @felmue for the information and pointing me to the source!
I've edited the main.c file and tried to build and flash the code via the Espressif IDF. I'm getting a lot of errors, and i'm unable to build the code. (i'm lacking coding experience to solve it)
According to this Youtube clip the errors may be caused by the version of the IDF. I've tried different older versions (I cannot find V4.0.3 anymore)

Can you help me any further with this?
Kind regards,
Joris

Hello,
I've burned the official Timercam v1.1 firmware to the Timercam OV3660. This functions very well and the image is visible via the api interface.
The only issue I have is that the device doesn't sleep longer than 2100 seconds (35 min). I've set the deep sleep time on 15000 seconds through the interface. The serial monitor also shows this sleep time when waking up.
It looks like the same issue as described here: Link to same issue.
Can I edit the firmware downloaded from the M5burner or are there other solutions to troubleshoot or solve this?

Kind regards.