UART boot VS download boot Trouble

[IngFormacion]

We design a hardware that will be controlled by the ESP32 WROVER, the ESP32 goes in an external shield, when I connect the shield directly to my computer, I can normally enter the download boot:

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1. rst: 0x1 (POWERON_RESET), boot: 0x23 (DOWNLOAD_BOOT (UART0 / UART1 / SDIO_REI_REO_V2))
2. waiting for download

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And I can upload any sketch normally.
But when I put the shield on the hardware designed by us, when performing the same procedure to enter the download boot, I get the following message:

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1. rst: 0x1 (POWERON_RESET), boot: 0x2f (UART_BOOT (UART0))

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The message "waiting for download" does not appear, and logically I cannot upload any sketch in this state.

I am not using the SPI pins of the internal flash memory, the GPIO12 is being used as an output so it should not interfere, I still put it on the ground and in vcc but the problem persists.

The Tx and Rx wires when connected to the hardware pass directly to the computer, just like on the shield.

[WiFive]

GPIO2 must also be either left unconnected/floating, or driven Low, in order to enter the serial bootloader.

[IngFormacion]

GPIO2 must also be either left unconnected/floating, or driven Low, in order to enter the serial bootloader.

Thanks, I put a resistance between GPIO2 and GND and problem solved, although I do not know why, I have worked with ESP32 before and had never had this problem, in fact on the shield the GPIO2 is floating and correctly enters the Download boot, in the complete hardware GPIO2 has a resistor that connects it to 3.3V and it didn't work, I had to put the resistance to GND too.