Flashing ESP32 WROOM 32D

[Harold_DR]

Hi there!

We are a group of 3 students who study Applied informatics and Internet of Things at Thomas More Hogeschool in Geel.
In the course 'Embedded devices essentials', we got the assignment to build a weather balloon from scratch.
We designed our own Printed Circuit Board at JLCPCB, which contained a ESP32-WROOM-32D chip.
We have received our boards, but it seems that our board is always resetting. This is the output from our serial monitor:

rst:0x7 (TG0WDT_SYS_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:1
load:0x3fff0030,len:1344
load:0x00000000,len:-1
ets Jun 8 2016 00:22:57

rst:0x10 (RTCWDT_RTC_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:1
load:0x3fff0030,len:1344
load:0x40078000,len:13924
ho 0 tail 12 room 4
load:0x40080400,len:3600
entry 0x400805f0
ets Jun 8 2016 00:22:57

rst:0x3 (SW_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:1
load:0x3fff0030,len:1344
load:0x00000000,len:-1
ets Jun 8 2016 00:22:57

When troubleshooting this, we found that these outputs can be generated because the device has no running configuration and needs to be flashed first.
We have already tried many different versions of the espressif flash tool, but none of them seems to work. Do you have any advice to guide us with our project?
Thanks a lot in advance!

Kind Regards,
Harold De Ridder

[ESP_Sprite]

I think you first need to figure out why flashing doesn't work, rather than why the chip is not booting. Can you post the output of a flashing attempt here? (Preferably one which is done using esptool.py, which is the default for arduino and esp-idf). Can you share the schematic of your PCB here?