FPGA fried?! Heatsink required?!

I encountered a problem with the DE10-Nano dev board a week ago:

After flashing a new fpga firmware, the Cyclone 5 SE chip doesn’t seem to work anymore.
Programming in Quartus Prime 19.1 still works, but the chip doesn’t seem to actually run the programmed circuits.
(I don’t get the expected results like blinking LEDs or clock signals on the output pins.)

Also, when I flash the Angstrom- or the console image, I get the following error showing up on the UART serial connection:

U-Boot SPL 2017.03-rc2 (Mar 30 2017 - 19:07:16)
/data/de10-nano/release-build-2017.03.31/build/tmp-angstrom-glibc/work/de10_nano-angstrom-linux-gnueabi/u-boot-socfpga/v2017.03+gitAUTOINC+d03450606b-r0/git/drivers/ddr/altera/sequencer.c: Preparing to start memory calibration
/data/de10-nano/release-build-2017.03.31/build/tmp-angstrom-glibc/work/de10_nano-angstrom-linux-gnueabi/u-boot-socfpga/v2017.03+gitAUTOINC+d03450606b-r0/git/drivers/ddr/altera/sequencer.c: CALIBRATION FAILED
/data/de10-nano/release-build-2017.03.31/build/tmp-angstrom-glibc/work/de10_nano-angstrom-linux-gnueabi/u-boot-socfpga/v2017.03+gitAUTOINC+d03450606b-r0/git/drivers/ddr/altera/sequencer.c: Calibration complete
SDRAM calibration failed.

ERROR ### Please RESET the board

Is there anything I could try to pin down the problem?
Could it be a faulty hardware?

I noticed the chip gets quite hot even if I don’t program it (no SD Card inserted).
I measured up to 90°C on the Cyclone 5 and the ram chip. Is this temperature to be expected?

Maybe I need an additional heatsink for my design?

In the mean time I ordered a new De10-Nano and indeed, it seem to be a hardware issue. My old dev board doesn’t boot with the factory SD card. The new one does…

Which heatsink should I buy, if any?

All the best,
Clemens

image

These are the results of the quartus power estimator tool for my design.
Shouldn’t it be safe to draw up to 1W?

I noticed, in Settings->Operating Settings and Conditions->Temperature, the max temperature was set to 100°C not 85°C (for consumer grade device). Does that matter? Would it be possible to fry the chip, when messing up this setting?!

Thanks in advance,
Clemens